It's the Brewers 2001 home opener, and Dubya's in the house -- the home clubhouse, that is -- to inaugurate the new ballpark. The prez is working the room before the main event, throwing out the first pitch. He teases shortstop José Hernandez, who played for the Rangers when Bush owned the team. Then the first fan congratulates Ben Sheets, who pitched the U.S. to gold in the 2000 Olympics. Finally, Bush approaches Richie Sexson, the 6'7" fungo-thin, bottle-blond first baseman, who hands the president a pen and asks him to sign a ball. Smirking, Bush glances at the suits in sunglasses behind him, then turns back to Sexson. "This better not be one of those exploding pens," the Leader of the Free World says. "I don't think the Secret Service would appreciate that."

The president of the United States calls you out when all you want is an autograph? That's how your rep as the biggest practical joker in baseball is cemented. But it's a title that Sexson had been working on for years. As a kid growing up in Hockinson, Wash., a town without a stoplight or a postal code, Richie once convinced his parents that he was a boy genius by correctly answering every question on Jeopardy! (They learned later that he'd watched the same episode on the family satellite dish an hour earlier.) As a minor leaguer in Buffalo, Sexson repeatedly prank-called his pop with fake interview requests from local radio stations. And as a rising power hitter in the majors, he doled out exploding golf clubs to his brother and father. "He's pulled so much stuff," says big brother John Jr. "It's gotten way out of control."

No sport offers a more fertile forum for high jinks than baseball. The minor leagues, with their numbing mix of small towns and long bus rides, are a testing ground for everything from the deft placement of whoopee cushions to the theft of a teammate's clothes; from putting Icy Hot in a pal's jock to filling his shoes with shaving cream. But every team, in every sport, has a Richie Sexson -- a guy whose angelic grin masks a devilish capacity for wreaking locker room havoc. "When players are asked what they miss most about being out of the game, they say the guys in the locker room," says ex-49ers tight end Brent Jones. "What they mean is the jokes."

So forget April Fools' Day. We're honoring practical jokers not just because April 1 is this issue's cover date, but because they're the unsung catalysts of team chemistry as well; fun-lovers who unite the clubhouse, free spirits who keep skaters loose when their team is one point short of an NHL postseason spot, fools who lighten the mood during the endless grind of an NBA playoff run. These jokers understand the locker room is a petri dish for experimenting with the kind of gross-outs that can bring a team together. "I had no idea about Richie's stupid human tricks," says Brewers manager Davey Lopes. "He changed the atmosphere around here immediately. You need guys like that in the clubhouse."

Yes, you do. But, like everything in sports, you also need rules to keep the laughs coming. Sexson, like all sports pranksters, lives by four of them.

RULE 1: No joke goes too far or too low.

With today's pros having the bucks to pull off the most impractical of practical jokes, the modern athlete has no place to hide if a teammate wants to put one over. A few years ago, when both men were Mariners, Ken Griffey Jr. lost a bet to Lou Piniella. The stakes? A steak dinner -- or so Piniella thought, until Junior deposited a live cow in his manager's office. And those were real cops who were persuaded to interrupt an AHL Hamilton Bulldogs practice, informing bruising wing Georges Laraque (now with Edmonton) that the only way to avoid jail time for speeding tickets was to dance the hokey pokey. In uniform. His performance, caught on camera, aired on the 6 o'clock news. "There's no mercy with this stuff," says Raptor guard Dell Curry. "Anyone can be made to look as foolish as possible."

In fact, the culture of clubhouse pranks can be so consuming that players sometimes forget to leave the fake vomit at the ballpark. When he was injured and not traveling with the team, Mariners RF Jay Buhner would sometimes cover his wife's toilet seat with plastic wrap and stuff baby powder into her hair dryer. And if such gags seem, well, pedestrian, welcome to the big leagues. Sexson once walked around the team plane with a whoopee cushion in his back pocket while Geoff Jenkins controlled its release via remote. That's typical Sexson: trying to pull teammates into his circle, not push them into therapy.

Last year, his first full season in Milwaukee after coming over in a trade from Cleveland in 2000, Sexson slammed 45 home runs and drove in 125 runs, and signed a four-year deal worth $17.5M. Which leaves him with serious disposable income to put toward causing trouble. Not that he didn't spend what it took before then. "We always had a supply of shocking cans and exploding pens and things like that," says Ted Walsh, the Indians clubhouse and equipment manager. "Richie loves that stuff. We'd go to Jack's Joke Shop in Boston or the House of Magic in San Francisco and load up."

RULE 2: Stay on the good side of the man who handles your jock.

To every player in every team sport, this truth is self-evident: The equipment manager is the one guy you need on your side. Treat him right, and he'll protect you. Treat him wrong, and even the biggest gamer becomes fair game. Walsh, over an 18-year period as assistant equipment manager with the 49ers and six years with the Indians, has trained a generation of merry pranksters.

During Walsh's stint in San Francisco, he encouraged QB Bill Musgrave to leave chewed chocolate PowerBars in Steve Young's helmet. They looked like something that had been, uh, digested. Every time, Young would ask Walsh if he knew who could do such a thing. "Bless his heart," says Musgrave, "Steve was never suspicious of anyone."

Walsh introduced Brent Jones to the exploding wallet, which Jones left lying around so often his teammates finally refused to bite. On one charter flight, Jones put the wallet in the middle of the aisle. An hour elapsed; no one approached it. Then Jones stuck a $20 bill inside, with part of the bill peeking out. No takers. After a while, Jones, who was sitting next to Walsh, forgot about it. Then coach George Seifert picked up the wallet. Bam!

"George jumped and screamed like an 8-year-old girl," says Jones. "Me and Teddy just put our magazines over our faces. Seifert looked at us and yelled, 'I know you guys did this! You're not getting your $20 back!'"

So when Sexson joined the Indians, the master found a prize pupil. "Richie has this laugh like a hyena's, and he goes off if you turn the doorknob the wrong way," says Indian slugger Jim Thome. "When Teddy realized that, he knew he had a new sidekick." Once, when the Indians were in Boston, Sexson left two of the duo's favorite toys -- the beer can that shocks when you lift it; the pen that jolts when you click it—on top of the guest-ticket list in the clubhouse. One by one, players would stop by to sign friends up, get zapped when they moved the can and zapped again when they touched the pen. And one by one, each replaced the can and pen for the next victim. Then along came Robbie Alomar.

"I left the clubhouse for a second and everyone is laughing at the next guy who gets buzzed," says Walsh. "I come back and everyone is real quiet. I ask Richie what happened and, with this hangdog face, he tells me, 'Robbie got mad and made us stop.'" Explains Sexson: "You gotta be careful who you get. Robbie broke that can. Some guys just don't want to be messed with." Shortly after the incident Sexson was traded. Coincidence?

"Um, yeah," says Walsh. "Probably."

RULE 3: Don't get mad. Get even.

Jocks being jocks, backing down is not an option. Last season, Patriots QB Drew Bledsoe got into it with his then-understudy Tom Brady after the latter locked the former's pads in Bledsoe's car and hid the keys. Taken aback by Brady's bravado, Bledsoe packed the AC vents of Brady's pickup with glitter and confetti. The next time Brady cranked up his ride, it was Times Square on New Year's Eve. Bledsoe then lined Brady's socks with tracing powder that turned the kid's feet purple for three weeks. Brady never really struck back -- unless you count taking Bledsoe's job and winning a Super Bowl MVP as payback.

A serious practical joker, though, will not simply retaliate; he'll raise the bar. During Arizona's 2001 run to the Final Four, Wildcats Gilbert Arenas and Eugene Edgerson engaged in a long seesaw battle that started when Edgerson spread mud on Arenas' freshly washed Lexus. In response, Arenas deflated the tires on Edgerson's Honda and encircled it with large rocks. Edgerson then stole Arenas' cell phone, leading Arenas to flood Edgerson's motel room with an emergency fire hose. The back-and-forth ended only after a team aide ratted Arenas out to coach Lute Olson, who pulled Arenas from the starting lineup that night.

Given their status as prime targets for jokes and other forms of hazing, rookies are naturals for the payback prank. "At some point," says Brewers centerfielder Jeffrey Hammonds, "they just get fed up." Whatever the sport, for example, nearly every first-year player ordered to bring doughnuts to the veterans has dipped the goods in paraffin wax. "I think it's actually a good thing when the rookies come back at you," says Sexson. "It shows us that they're not afraid." As when Saints rookie wideout Anthony Collins deposited a live boa constrictor in veteran Joe Horn's bag during training camp last summer. "I almost died," Horn said at the time. "I hate snakes worse than flying."

Sometimes, though, even the best-conceived pranks don't work. This spring, after ex-Reds Pokey Reese and Dmitri Young called Ken Griffey Jr. a bad teammate, Adam Dunn persuaded a writer to rig a fake Columbus Dispatch Web page headlined "Rookie Dunn the Latest to Rip Griffey." Dunn printed the page out and placed it with other newspaper clippings in the Reds Sarasota spring training clubhouse. Unfortunately for Dunn (or maybe luckily), Griffey didn't take the bait -- perhaps because the story said Dunn was tired of Junior leaving the dugout to masturbate.

RULE 4: Know when to say when.

The brooding superstar? Let him be. The veteran who's just hanging on? Leave him some dignity. The rotation ace who hasn't got out of the fourth inning in his last four starts? Hands off. Pranksterism is an art form that requires more than one kind of discretion.

"A gag won't wash after a five-game losing streak," says Sexson. "The front office doesn't want to see you smiling too much." With the Brewers, then, Sexson's sense of timing is all the more important. "Richie has an innate ability to know who you can get and when you can get them," says Lopes. "Otherwise things like this can do more harm than good."

Exhibit A: Tim McKyer. The ultramouthy former 49ers CB spent most of the 1989 preseason calling himself The Blanket. After he was toasted in the season opener against the Colts, Joe Montana hung a baby blanket, singed around the edges and featuring McKyer's No. 26, on a locker room bulletin board. McKyer missed the next three games with a "pulled groin." When coaches asked him to play through the pain, he lashed out at them, was suspended for insubordination and lost his starting job. The next year, he was a Dolphin.

At least McKyer was able to walk. The day before the Eagles broke training camp in 1992, Mike Golic and his D-line peers went to Wal-Mart, picked up some Super Soaker squirt guns, bribed the team's security guards to lock the dorm doors and went room to room blasting teammates. A sleeping Fred Barnett didn't take it so well. When Golic sprayed him, the angry WR jumped out of bed and collided with a desk, suffering a deep thigh bruise that kept him out of the opening game. "Man," says Golic, "did we hear about it from the coaches."

Prank-pulling is an even more delicate art now that sports has become so international. In 1996, returning to the locker room after pitching three hitless innings against the Cubs, Dodgers rook Chan Ho Park found his suit cut into a Bermudas-and-short-sleeve ensemble. Teammates thought they were welcoming Park to the club. But something got lost in translation. The enraged South Korean pitcher started throwing food, furniture and four-letter words around the clubhouse. Apparently, in Korea, cutting someone's clothes is the ultimate symbol of humiliation. Oops.

The master prankster is ahead of the curve when it comes to international rules. Having been forced to don a dress after a game in KC during his rookie year, Sexson is already planning when and where he'll get this year's freshman class. "Canada," he says. "It's gotta be Canada because they have to walk through the airport to get to customs." As he says this, Sexson is eating lunch in the Brewers spring training clubhouse in Phoenix. Hammonds, the centerfielder, sits next to him, and pitcher Nick Neugebauer, an August call-up last year, is next to Hammonds. When Sexson turns to watch golf highlights on TV, Neugebauer whispers to Hammonds, "You know, no one ever got me in a dress last year."

"Oh, yeah?" Hammonds says. "Well, keep it quiet. You don't want it getting around. Meantime, maybe you can get me some Gatorade."

As Neugebauer rushes off, Hammonds smiles at Sexson: "Just a kid who wants to stick around with the big boys. Doesn't know any better."

"Yeah," Sexson says. "We'll get him in Canada."

This article appears in the April 1 issue of ESPN The Magazine.