A phrased mainly associated with the arts of picking up women or "bitches" by figuratively "throwing bones" to them, which is to flirt, mack or game on them with the intention of getting a woman or bitch to eat the bones which is to fall for your game ultimately leading to seduction.
"I was throwing bones at this girl last night, and she ended up going home with me"
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.