Fo’ rizzle, dizzle: A short history of izz and izzle
[...]The infix izz appeared early during the gestation of hip hop— emerging in the 1985 song “Roxanne Roxanne” by the Brooklyn rap group UTFO. While izz didn’t immediately integrate into common vernacular, it did flower in avant-garde hip hop. For instance, the izz re-emerges in the 1991 Another Bad Creation song “Coolin' at the Playground Ya’ Know” with the lyric “Into the Mizzark chillin in the pizzark … mother said be home by dizzark.” [...]
This article presents a fine piece of etymological detective work. I was always under the impression that izzay and izzle, as in Snoop Dogg's famous fo' shizzle 'for sure' originated with Snoop, back on Dr. Dre's The Chronic album (1992). This article puts the infix at least seven years prior to that in 1985 with UTFO.
Interestingly, the infix has ingrained itself in the language to the extent that it has apparently undergone at least minor semantic shifting, as is evidenced by the several entries at urbandictionary.com. Check it out fo yo sizzelf.