When you’re about to ejaculate on a victim, and you instead turn around and ass-to-face fart on them.
“Yeah bro not kidding! On April fools, I about to bust on my girl’s face and I pulled a Poo Diddy and whipped my shit around a took a massive fart on her tongue.” - Brady
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.