This is when you are having sex with a woman on her period. You pull out and quickly put it in her mouth. As you can imagine, your penis would be bloody so putting in her mouth would result in her lips getting red all around, kinda like a clown's make-up. This results in a Crazy Clown.
Damn dude, last night Becky didn't tell me she was raggin', so I paid her back by making her a crazy clown.