When you want someone to shut their whore mouth so you want to insert your big toe in their mouth to shut them up, but that wouldn't be publicly appropriate so you say "suck a toe" instead.
Erin: Hey guys, wanna hear a story!?
Everyone: SUCK A TOE!
To tell someone to suck a toe, is essentially the mash up of “fuck off” and “kiss my ass”, in a much more PG way, and is much more socially acceptable in an environment with slightly less than chill adults.
Guy 1: oh my god, why would you stab my hand with your pencil?!
Guy 2: I’m sorry man, I didn’t see it there.
Guy 1: Jesusdude. Go suck a toe.
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.