Most fans would keep the souvenir, but one Boston Red Sox was fed up.
During Saturday's game against the New York Yankees, slugger Giancarlo Stanton hit a home run over the left field wall at Fenway Park.
The Boston fan who caught the ball, immediately threw it back toward the field, hitting Stanton as he rounded the bases.
Stanton acknowledged the fan and even poked fun at the incident on his Instagram. The fan who threw the ball ended up getting ejected.
Stanton's home run was New York's major league record 266th home run of the season, and Stanton's 100th RBI on the year.
The Yankees ended the game with the last laugh as they defeated the Red Sox, 8-5.