A container into which CIA, FBI, NSA personnel and others place sensitive or classified working materials, shredded or not, to be destroyed on a regular schedule--daily or more often.
"As soon as you've finished reading that transcript of the President's private comments to the Prime Minister, be certain it goes into the burn bag."
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.