A combination word used to describe something which is extremely large. Larger than life. Derived from "gargantous" and "gigantic."
"Someone told me that Lou Ferrigno was smaller than Arnie; like he was only five foot four or something! WRONGO! I saw him at a downtown nightclub! They practically had to take the door off the hinges so he could get in. He's gargantic!!"
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.