A pisstickle is basically wanking in the bath. The reason it has the name Pisstickle instead of bath wank is because when you jizz in the bath it look like white piss. And you have tickle your Willy in the bath at least I do!
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.