Boobs that are freakishly large or just awkward in shape. May look like two clown shoes stuffed in a bra or two carnies stuffed in a bra. Usually the girl with the clowntits thinks she has the best boobs in the world and puts them out there for everyone to see.
Stacey: Oh my God, look at that girl's boobs!
Lacey: Oh my God I know. What's wrong with them?
Stacey: They're clowntits.
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.