What is -izz-?
The midfix -izz- is used as an embellishment to add syllables to words, perhaps for purposes of meter. When context allows, sometimes the remainder of the word is actually omitted.
Regular: "I'm going out to walk the dog."
Instead: "I'm going out to wizzalk the dizzog!"
Or: "I'm going out to wizz the dizz!"
Clarification: the -izz- is placed after the initial consonant, or if the word begins with a vowel, at the beginning of the word.
"Ow, I banged my arm!"
"Ow, I bizzanged my izzaarm!"
"Ow, I bizzed my izz"
It is simply ebonic pig latin.
Pig Latin becomes Pizzig Lizzatin.
Fo' Sho' becomes fizzo shizzo, or fo shizzo, which then became shizzle, in and of itself a new slang word.