Check out this wild video -- obtained by TMZ -- showing a dude who walked into Harrah's Sunday night in nothing but his birthday suit ... casually walking into the casino and making his way to the poker tables, where he really got the show started in front of everyone.

With beans and frank on full display, he hops up onto a gaming table and starts gyrating on the felt. Patrons were clearly shocked, but casino workers just seemed pissed and reviled -- one woman was dry heaving after getting an eyeful.

Security was flagged almost immediately, but before they arrived nature boy put all his "chips" on the table -- laying on his back, and going spread eagle!!! When he started grabbing cards and chips, he got the hook as 3 guards hopped on him and detained him until cops showed up.

We obtained the police report which says cops were called originally because the man had assaulted someone at the Flamingo Hotel and fled. As they were trying to locate him, he was detained by Harrahs security who said he'd been seen removing his clothes next door at The Linq Hotel.

Lots of people talk about going balls to the wall in Vegas, and then there's this guy ... who got booked for 2 misdemeanors -- indecent exposure and disorderly conduct.