1. an individual who can frequently be seen slapping his own gooch
2. an individual who can frequently be seen slapping the gooch of another individual
Jim: Hey Taylor, you'll never who I just walked in on in the bathroom, slapping his own gooch!
Taylor: *gasp* Who?
Jim: Bob! I walked in to take a piss and there he was just standing in the stall with the door open, punishing his gooch!
Taylor: Wow... I never would have seen Bob as a gooch slapper...
Jim: I'm not sure if he saw me. I hope he didn't, I don't want him slappin' on my gooch.
It is said of the situation where a person has the bad luck to make contact with his testicles against an undefined surface or object, intentioned or not.
Given the nature of the word, it is more appropriate to design cases where the interaction is made with a moving object, for example, a ball.
Although it is extremely painful for the victim, it tends to be considerably funny to people who witness it.
Today in the baseball game the pitcher took a nutshot; the baseball hit him in the nuts.
Man, I just watched the funniest nutshot video ever.