It's a more calmer way of saying
the curse word "shit", used in various
expressions and ways .
Or another way of saying the slang "fo sho" to "
fo shizzle"
Girl 1:
Oh shizzle I just left my food..
Mom: Hey?!
You know aren't allowed to curse until your thirteen
Girl 1: Mom chill, I didn't even say a curse word I just said "oh shizzle" geez
Mom; Oh! Okay..
OR..
Boy 1: Yo, you headin' to Drakes concert too?
Boy 2:
Fo shizzle // Fo sho
Boy 1: Aightt see u there "Boy 2"