this is a song used in Episode 16 - Roborapper, the lyrics go like this:
Hey, Flap, Flap, you're the reason we rap rap
You make my booty rat-ta rat-ta
The way you do it like that
Hey Flapp, Flapp, (thats me) you're the reason we rap rap
You make my booty ratta tat they way you do it like that