When a man wears pants that are too tight and the seam of those pants where the two legs meet in the middle split your balls leaving one ball on either side, leaving the seam in the middle of the balltaco. Not unlike a male camel toe.
usually when a chick is really loose or is older. When she is wearing panties and it looks like she could be packin' some heat inside of them. When you pull the panties off and she is so loose you can squeeze both of those taco lips together and it looks like a double double.
you-"I got with this milf last night"
friend-"awesome, how was it?"
you- "it was was amazing! I will never go back to young chicks, I just love it when they have a nice big ballsack taco"
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.