spitball

Concise Oxford English Dictionary © 2008 Oxford University Press:
spitball /ˈspɪtbɔːl/ N. Amer.

▶noun

• 1 a ball of chewed paper used as a missile.

• 2 Baseball an illegal swerving pitch made with a ball moistened with saliva or sweat.

▶verb informal throw out (a suggestion) for discussion.

– derivatives
spitballer noun.