Used metaphorically to refer to the absence of someone who is called out, particularly when that person is in a queue. It is commonly used in a clinic setting where in a patient leaves before his or her turn is up.
"Patient X was not outside when I called his name."
"He's out went cold."
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.