When you are getting it on with somebody anally, totally in the
moment enjoying the friction and tightness of a firm asshole and they happen to cum so hard that they
literally shit on your balls and completely ruin the
moment!
When you visit your
doctor cause your peehole stings like a motherfucker and you think it's because of the bacteria from all that butt fucking, only to have the
doctor tell you. "No
sir... it's not bacteria, it's the Clap!" That is when you have the right to yell "Shitballz!"