Slang or a shortening of "What is the deal, yo?". Pioneered during the Howard Stern program by one of the characters, roughly during the "O.J. Trial"
Yo, dat shizzle be wizzle, G. What the dilly-o, vato?
Actually spelled what the deally yo?
This term came from the hip hop song Put Your Hands Where My Eyes Could See - by Busta Rhymes. From the When Disaster Strikes album released in 1997.
Verse - "Silly with my nine milli, what the deally yo?"
It's a slang term meaning "What's going on?". It actually derives from "What is the deal yo?"
"Yo, I thought we were all going to the club. Now you guys just wanna chill. What the deally yo?"