A ring of muscle surrounding the opening of the body that lies in the anal area.
A butthole.
Example:
Kraig: "Hey Sharon, can you pass me the salt"
Sharon: "Oh yeah, sure not a problem. But I'll have to warn you I've been itching my meatring for hours and it might be a little gross."
Kraig: "Hahaha. Oh Sharon, we've known eachother for years. You might be a discusting person, but your a strait shooter and I've gotta respect you for that."
Sharon:"We've been friends for years and you know kraig that really means a lot."
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.