A vocal utterance that signals anyone more culturally sophisticated than an orangutan to pick you up and throw you off a cliff for the good of all mankind, even when used jokingly. Similar middle school esque blurps include "swag", "yolo", "snap", "gangsta", "raped", and "owned".
Jason: My girlfriend dumped me, but at least I got accepted into UFV
Bryan: Oh burn
Jason: You're 28, uneducated, work at Wal-Mart, live with your mom, and you talk your balls just dropped. You aren't in any position to be "burning" anyone. Ever.
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.