A spitball is a (now illegal) baseball pitch, in which the ball has been altered by the application of saliva, petroleum jelly, or some other foreign substance. Alternative names for the spitball are spitter, mud ball, shine ball, supersinker, vaseline ball (because Vaseline was used to give the ball a little more break), and emery ball.
The spitball was banned in two stages. In the winter of 1919–1920, managers voted to partially ban the spitball, allowing each team to designate at most two pitchers who would be permitted to legally throw spitballs. Then, following the 1920 season, the spitball was banned league-wide, except for 17 existing spitballers who were grandfathered in and allowed to keep throwing the pitch legally until they retired.