Bumjiggalo is a term coined by a 20 year old sophomore at the University of Arizona in 2007. She came up with it as a nicer way to call her boyfriend an asshole. Its such a catchy word that she subsequently used to describe any person or thing as "Punk-like" in the way that some one is frustrating or annoying (not punk as in the style).
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.