October 2, 1978: AL East rivals Boston and New York - each with 99 wins at the end of the regular season - are facing off in a one-game playoff for the American League East division crown. The Yankees are down, 2-0, in the seventh inning with two men on when Bucky Dent walks up to the plate. Dent, who, with four homers and 37 RBIs on the season, was not known for his power, knocks a three-run homer to left field over the Green Monster, putting the Yanks up, 3-2. The Yankees went on to win the game, 5-4, and advance to the ALCS.
Dent originally stepped to the plate with a different bat, but after fouling a ball off his foot, he borrowed teammate Mickey Rivers' piece of lumber. It was with that club that he hit his famous homer. To add to the lore (it's not every day a guy with only 40 homers over his 12-year career hits such an important shot), the Yankees had been 14 games behind the Red Sox in mid-July.
Though it didn't prove to be the game-winner (a solo homer by Reggie Jackson in the eighth was) Dent's unlikely homer was the final straw for a Red Sox Nation still (at the time) suffering under the weight of the Curse of the Bambino. Dent has been known to Red Sox fans as Bucky "Bleeping" Dent ever since.