The patch of hair at the base of the spine, just above the start of the butt crack. Usually found on men. Resembles a traditional bush, just located on the opposite side.
Ex) That guy's pants were hanging so low, I saw his butt bush.
Ex) He's so hairy...he needs to wax his butt bush!
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.