Somebody who accuses other people of being fanboys over something, and then continues to say something themselves which is considered fanboy-ish.
Fanboy: Windows is rubbish man! Macs are so much better because you never get viruses and you don't kiss Bill Gates' ass!
Fannyboy: Shut up you stupid fanboy! Windows is so much better than crappy Mac, Macs are completely stupid and Windows is so much better because you don't kiss Steve Jobs' ass!
A Person: Wow, you are such a fannyboy, you call other people fanboys then be a fanboy yourself.....
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.