"That is off the hook for real" would be the literal meaning of the phrase. It means that something is extremely novel and interesting, and that you're dumb enough to think you sound cool adding "izzle" to the end of your words.
Dude A: Hey dude, have you seen Frank's new car?
Dude B: Why yes I have. That tizzle off the hizzle foshizzle.
Dude A: WTF?!?!?!
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.