A Shit-Jerker is when you have to take a poop and you sit on the toilet and hold it in while you jerk your cock hard, and then right when you are about to cum you squeeze your ass muscles like fresh lemonade and you expel a Giant turd boat out your ass canal while a milky stream of shimmering white cum flies out your dickhole.
Yo did you hear that Tommy got fired yesterday, I guess the boss caught him taking a shit-jerker
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.