As used in the 50's, the sweet or tangy goop that comes from a woman when she "gets off". Or, "gettin' some" from a female.
"Damn, her poo-tang pie tasted sooo good, it was sweet too, she must have been drinking orange juice!"
Or:
"Hey, rememba dat bitch i was tellin ya'll 'bout!!? Well, she finally let me take a dip into her poo-tang pie and it was off the chain!"
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.