Kristin Cavallari at Magic Mike Show in Vegas

Kristin Cavallari is living it up like a single lady -- and doing so with the help of some hunky Magic Mike dancers in none other than Sin City.

The reality star was in Vegas Saturday night where she was taking in the shirtless sights at the SAHARA hotel -- and wouldn't you know it ... she was actually lucky enough to get dragged onstage by one of these hunks.

In video obtained by TMZ, you can see KC getting a full-blown lap dance of sorts -- albeit one that had her lying flat on her back -- while the dude went to work on the whipped cream.

He sprayed some on her neck and licked it off, and then went for her legs -- at which point Kristin got a little slap-happy with his ass. Eventually, he was straddling her ... and squirt a little cream on his chest for her to get a taste -- but things were cut short after that.