Lil Jon Dumps Ice On Twerker -- This Girl's Ass Is On Fire!!! [VIDEO]

WHAAAT! Things got way too hot for Lil Jon in Vegas last weekend -- some hot blonde chick twerked her ass off at his table ... and the rapper decided she needed to chill ... with a glass full of ICE CUBES.

The video was shot Sunday night inside XS Nightclub -- it's pretty wild ... and Lil Jon obviously knows talent when he sees it ... because the girl in the clip has serious skills.