spitball

[spit-bawl]

noun

a small ball or lump of chewed paper used as a missile.
Also called spitter. Baseball. a pitch, now illegal, made to curve by moistening one side of the ball with saliva or perspiration.

Origin of spitball

An Americanism dating back to 1840–50; spit¹ + ball¹

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Then take a wrapped straw, unwrap it, tear off a little piece of paper and make a spitball.
Why the Biathlon Makes Bonds of Us All
Brett Singer
February 16, 2014

But the very first "spitball" which spattered upon the blackboard proved a disastrous missile for its thrower.
Cy Whittaker's Place
Joseph C. Lincoln
I thought I could go through the motion of throwing a spitball without letting it go.
The Iron Puddler
James J. Davis
Hooper was a spitball artist, and his moist slants kept the Giants guessing in the early part of the game.
Baseball Joe, Home Run King
Lester Chadwick
He had never cared for the spitball, as he knew that sooner or later it destroyed a pitchers effectiveness.
Baseball Joe, Home Run King
Lester Chadwick
There are also other modifications called "the fade away," "the spitball," and others.
Outdoor Sports and Games
Claude H. Miller

1846 in the schoolboy sense; 1905 in the baseball sense, from spit + ball (n.1).