When a person has been so absorbed in what he/she believes to be true, that no amount of reality, logical or factual explanation or actual proof, to show them that their believe is 100% wrong, will convince him/her otherwise.
The acronym "tfg" is mostly used. (Especially used in political discussions)
Your logical explanation of the facts are falling on deaf ears, because he is too far gone!
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.