Between 1970 and 2003, six major league baseball players in the United States were caught using corked bats. As of 2015, Sammy Sosa was the last pro player to be caught using a corked bat, for which he was suspended for eight games in 2003.
In at least two of these cases, the material inside the bat was not actually cork but rubber balls. As punishment, all of these players were suspended for at least seven games, and one, Chris Sabo, who was caught using a bat stuffed with rubber balls in 1996, was fined by his team. A corked bat is a bat that has been illegally modified to be lighter.