spitball

nouns

a projectile made by chewing a piece of paper and shaping it into a sphere
spitball
is a type of (narrower)
a weapon that is forcibly thrown or projected at a targets but is not self-propelled
missile, projectile
an illegal pitch in which a foreign substance (spit or Vaseline) is applied to the ball by the pitcher before he throws it
spitball, spitter