1. A short, roughly two second dance that involves a shimmy-like twisting motion whilst naked--best when done with a flaccid penis, so as to allow for a little wiggle.

2. A tactic often used to catch someone off guard (see Definition 1.)
"Damn! Chucho called my name and I turned in response only to find he had pulled an uncha-duncha on my ass!"
by Roach Brothers May 5, 2004
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