Definitions by Rob Echlin

monkey brains 

When you pull ur nut-sack out of ur pants/shorts while keeping ur dick in ur pants, thus makeing them look like a monkeys brain

"Hey billy, wanna see some monkey brains?" "sure why not"..........."EEEEWWWWWWW THATS UR BALLS!"

monkey brains by Rob Echlin July 22, 2004