screwball

Concise Oxford English Dictionary © 2008 Oxford University Press:
screwball /ˈskruːbɔːl/ chiefly N. Amer.

▶noun

• 1 Baseball a ball pitched with reverse spin as compared to a curve ball.

• 2 informal a crazy or eccentric person.

▶adjective informal crazy; absurd.

■ relating to or denoting a style of fast-moving comedy film involving eccentric characters or ridiculous situations.

– derivatives
screwballer noun.