When one is on the fence about an important decision, instead of "sitting on it" they "fap on it" (jerk it, rub one out, a good wank, etc.) then revisit the issue at hand with a much clearer mind and thought process. Usually pertains to issues involving bitches and hoes.
The term was coined in the famous rage comics on reddit.
Jim: Hmm I'm not sure if I should fuck my ex again. I know I'll fap on it.
* fapfapfapfapfap*
Jim: Nah fuck that bitch
Tom: Do I really need that new TV? Welp, time to fap on it.
*fapfapfapfapfapfap*
Tom: Fuck yes I need a new 60 inch plasma tv
To masturbate prior to making a decision involving women. "Fap" comes from the onomatopoeic representation of masturbation popularized on the internet via web forums.
When one faps on it, sexual tension is released through masturbation, resulting in a mind that is clear in thought and a rational decision can be made involving women, usually sexual decisions.
Bro 1: I'm not sure I want to drop $40 tonight on drinks with Jen at the bar. I wanna fuck her, but I don't know if it's worth spending dough on her.
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.