"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?!?!?!
a bastardization of "fo' sheezy mah neezy" which is a bastardization of "for sure mah nigga" which is a bastdardization of "I concur with you whole heartedly my African americanbrother."
"fo shizzle ma nizzle" is a bastardization of "fo' sheezy mah neezy" which is a bastardization of "for sure mah nigga" which is a bastdardization of "I concur with you whole heartedly my African americanbrother"