The act of male masturbation

Jack off.

To masturbate , usually associated with guys.

to punch your boner till you ejaculate

originally a reference to a children's toy. the clown (or whatever character-- i had heman) was a weighted bottom blow-up punching bag. it was designed to pop back up to a standing position when knocked over. essentially, punching the clown is a useless act which accomplished nothing. often used in reference to menial tasks and bureaucratic corporate jobs.

playing the skin flute.

To hit a clown on the face.