n. A devious act whereby a tradesman etc deliberately includes flaws in his work, thereby guaranteeing that you will call him back sometime in the future to fix them.
One of our radiators is broken! But our central heating system was fixed six months ago. I reckon the plumber pulled a billgates on us!
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.