Your dick after using bad toilet paper to clean off seamen from masturbating. The paper deteriorates leaving fuzzy white remnants, making your penis covered in cotton.
Guy: Dude I jerked it like three times today and now I have the worst cotton dick
Taken from the christmas movie 'Elf'. A 'Cotton Headed Ninny Muggins was one of the lowest forms of insult, it's meant to cause offence. A term adapted to 21st century language.
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.