W.T.F.S.M. means What the fucking shitting monkies. Used when something is just too outrageous to say Wtf to, and also makes you angry.
Boyfriend: Omg. Why do you complain so much. Just shut up already. Damn.
Crazy Girlfriend: Oh hell naw! You did not just tell me to shut up. I'm gonna have to cut you!
Boyfriend: Wtfsm?!