Charles Barkley -- BOOTY DANCIN' ... At Vegas Bar

GET IT SIR CHUCK!!!

We just got amazing video of Charles Barkley gettin' down -- droppin' it low -- at a bar in Vegas this weekend. Did we mention it's amazing?

Barkley was at the Mandalay Bay around 1AM Sunday morning -- busting out the moves to the beat of Kendrick Lamar's new jam, "i."

Clearly, Sir Chuck was feelin' it ... until the DJ decided to put on CeeLo's "F**k You" ... and that's when Barkley decided the dance party was over.