They booed Allen when he walked onto the team bus. They booed him when he arrived in the lobby of their team hotel. They even booed him during film sessions and when Allen touched the ball in practice.
So when Allen set back-to-back playoff career highs in Games 3 and 4 this weekend to help Milwaukee take a commanding 3-1 series lead over Chicago, the Bucks bench enjoyed booing him all the way.
"They have so much fun doing it," Allen said with a laugh after scoring 27 points off the bench in the Bucks' 119-95 victory Sunday afternoon. "I think it's honestly hilarious. They've kind of turned it into a fun thing. It makes hearing it out there during the game a lot easier, too, because they think it's so funny."
Game 5 will be Wednesday night in Milwaukee.
The Bucks began jeering their own teammate earlier this season once they heard the reaction Allen received every time he touched the ball during the team's first game in Chicago back in March. Allen became public enemy No.1 to Chicago basketball fans after his flagrant foul on Bulls guard Alex Caruso during a game on Jan. 21 resulted in a fractured wrist for Caruso, forcing him to miss two months.
Allen said Sunday that he had attempted to reach out to Caruso to apologize after the incident, but the two never connected. The Bulls downplayed any lingering animosity toward Allen leading up to the series, but fans at the United Center have not let it go as easily, responding with loud boos each time Allen approached the scorer's table or touched the ball on offense each game this season.
Even if he has gained a reputation as a villain in Chicago, Allen insisted after the game Sunday that he does not feed off such a negative reaction.
"It's not naturally comfortable for me," Allen said. "I am to the point now, anytime I go out and play basketball, I just remind myself to go out and have fun with this. ... My personality is naturally uncomfortable with the attention, the booing, the heckling. It's not something I feed off of. I'm not going out searching for it."
That hasn't stopped Allen's teammates from having fun with it.
Bucks star Giannis Antetokounmpo suggested Allen frame a photo from Game 3 in which the Bucks bench is in the background booing Allen as he heads to the free throw line after a converted and-1.
"He's played amazing, maybe we got to boo him even more," Antetokounmpo said with a smile after the game. "Maybe Milwaukee fans, we got to boo him ... nah, we're not going to do that."
Added guard Jrue Holiday: "When we booed him during the game, and he really started hooping, I think we just stuck with it."
After leading all scorers in Game 3 on Friday with 22 points, Allen was even better on Sunday afternoon.
Allen went 10-of-12 from the field on Sunday, including 6-of-7 from 3-point range, to outscore Chicago's bench all by himself 27-17. He became the first Bucks player to score 25 points and knock down six 3s in a playoff game in team history and first Bucks player with at least 25 points off the bench since Tim Thomas in 2003, according to research by ESPN Stats & Information. Allen even made plays on defense, collecting three steals and holding Chicago to 3-of-8 shooting when he was the primary defender.
Allen rebounded after going 0-for-4 from 3 to start the series in the first two games. His performance this weekend helped the Bucks withstand the loss of forward Khris Middleton, who will miss the rest of this first-round series with a sprained MCL in his left knee.
"He's kind of quiet, but confident," Bucks coach Mike Budenholzer said about Allen. "I think this is a confident group, a group that sees a player that can help them and appreciates his competitiveness. He's just quiet, no bulls---, and comes to play. I think our guys gravitate towards that type of mentality. It's certainly been a good fit."
By the time Allen checked into the game in between free throw attempts with 5:50 remaining in the fourth quarter, the boos from the crowd at the United Center had gone from full-throated to halfhearted.
Chicago had waited five years for a home playoff game here, and the fans' reward was a weekend of uncompetitive basketball. The Bulls were outscored by a combined score of 230-176 in the two games on their home floor and must win Wednesday to extend their season.
"You got to give [Allen] credit," Bulls guard Zach LaVine said. "He's hitting shots. ... Obviously, we know what happened [with the Caruso injury]. At the end of the day, it's basketball too. We understand it. But it's not like we're going out there saying, 'That guy can't beat us.' The Milwaukee Bucks can't beat us and he's part of their team. Them as a whole is beating us right now.
"You can't just account for him. It's everybody."