A person who constantly takes your pillow, that you yourself picked out, & switches it out with their shitty pillow that they picked out. They then proceed to act as if THEY picked out the good pillow, & you should take the shitty pillow.
Or, a person who has discarded a pillow because "I don't like it. It doesn't work." - Complaining Wife. Only to take it back, every night, after you (being the husband), rescued said pillow from a meaningless existence in the linen closet.
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.