When your high af and can't think of anything to say and what comes out is Schiiisch! Also may become addictive to the point of it being said uncontrollably around all your friends.
After the concert we smoked a shit ton and then we asked our friend how he was feeling, and all he said was Schiiisch!
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.