Proof that white kids steal everything from black culture, Chef wasn't serious about the term. :D Matt and Trey probably are also making a Bedknobs and Broomsticks reference for purposes of absurdity.
Mr Garrison: Chef, what did you do when white people stole your culture?
Chef: Oh. Well, we black people just always tried to stay out in front of them.
Mr Slave: How did you do that?
Chef: Well, like with our slang. Black people always used to say, "I'm in the house" instead of "I'm here." But then white people all started to say "in the house" so we switched it to "in the hizzouse." Hizzouse became hizzizzouse, and then white folk started saying that, and we had to change it to hizzie, then "in the hizzle" which we had to change to "hizzle fo shizzle," and now, because white people say "hizzle fo shizzle," we have to say "flippity-floppity-floo."
Mr Garrison: We don't have time for all that, Chef! Oh, if only those Queer Eye For the Straight Guy people understood what they were doing. Wait. That's it! I know exactly what to do! Come on, Mr. Slave! Let's get back to our flippity-floppity-floo.
Chef: Oh no! Dammit! Don't call it that!