Oscar De La Hoya just gave his fans a lot more than they bargained for ... throwing on a skimpy thong and doing a freaky dance with his partner, Holly Sonders -- and sharing the footage for all to see.
The wild clip was posted to the pair's Instagrams late Sunday night ... showing them barely covered as they grooved to Sak Noel's "Loca People."
It kicked off with Holly -- donning a tiny, pink thong bikini -- dancing solo .