To "do a Mientkiewicz" in baseball is to make off with the game ball from a big victory, usually unjustifiably. It references the time when Doug Mientkiewicz, a back-up infielder on the 2004 Boston Red Sox, kept the game ball from the team's World Series victory. The franchise threatened to take him to court for the ball before Mientkiewicz finally gave it to the Hall of Fame.
The back-up catcher did a Mientkiewicz and hid the game ball in his equipment when no one was looking.
by Emlove December 9, 2008