Diamond offense

• Child's missile
• A projectile made by chewing a piece of paper and shaping it into a sphere
• It uses liquid from a pitcher
• It's hard to hit
• Changing pitch
• An illegal pitch in which a foreign substance (spit or Vaseline) is applied to the ball by the pitcher before he throws it
• Cardinal sin?

Longman Dictionary of Contemporary English Word definitions in Longman Dictionary of Contemporary English
noun EXAMPLES FROM CORPUS ▪ Anna said they are the ones who score low grades and throw spitballs in class. ▪ I checked around for spitballs and paper wads. ▪ My memos are spitballs in the face of the faceless monolith where I work. ▪ The Operations students ...

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
1846 in the schoolboy sense, "bit of paper chewed and rounded as a missile;" 1904 in the baseball sense, from spit (n.1) + ball (n.1).

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
spitball \spit"ball`\, spit ball \spit" ball`\, n. Paper chewed, and rolled into a ball, to be thrown as a missile; -- a childish prank. (Baseball) A pitched ball in throwing which the pitcher grips the ball between two, or three, fingers on one side (which ...