What you call someone who falls asleep while hanging out with a group of friends. Usually passing out due to several substances in the body. Drunk or stoned. It's often accompany with a punch to the chest to wake the person up.
After several beers, Mark fell asleep on the couch while watching a movie. Zack yelled "Quit being a taternuts," and punched him in the chest.
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.