The act of masturbating during a church service. Most likely, it's the man sitting in the back row all by himself. He's been caught chapelbating before, but they don't want to kick him out of the church because they're trying to be good people. So, no one sits around that one guy in the back.
Man #1: "I think I hear that guy in the back Chapelbating, bro."
Man #2: "Yeah, he's that guy that does that. No one sits around him because of it."
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.