Ryan Lochte -- Devours His Birthday Cake ... Shirtless (VIDEO)

Ryan Lochte celebrated his birthday exactly how you would imagine he would ... without a shirt.

The Olympian/reality TV star was having his birthday dinner at Andiamo Steakhouse located inside the D Casino Hotel Las Vegas ... when he was dragged next door to where the Men of Strip were performing.

After a birthday serenade, the crowd implored Lochte to take off his shirt ... and he of course obliged. He then proceeded to take a sloppy bite out of his birthday cake ... still without his shirt on.