Guess who came to dinner?

Michael Phelps arrived at his mom’s Thanksgiving celebration with his new girlfriend — a tattooed strip-club waitress who has bared her chest for photographers almost as many times as the Olympic swimming star.

There was no word on how his 57-year-old school-marm mother reacted to Caroline “Caz” Pal [a 26-year-old cocktail waitress at the Moon Nightclub in the Palms Casino Resort in Las Vegas]

— and the prospect that she may some day dive into the family gene pool.

It was her first visit to the Phelps family home in Baltimore since the Olympian struck gold with her two months ago in Las Vegas, where she works at the Palms Casino, according to People magazine.

The pair had become so serious that Phelps felt ready to take the next lap with her, and bring her back to his Baltimore home.

Pal, 26, has posed for photos taken for risqué Web sites, including “Beverly Hills Pimps and Hos.”

Her MySpace page greets visitors with the welcome: “Baby, let me upgrade you.”

Phelps’ mom, Debbie, for her part, has spent 30 years teaching middle-school kids.

Her support for her 23-year-old son earned her the title “Official Mom of the Olympic Games.”

Phelps, who’s betting that the two very different women in his life will hit it off, is spending his time working on his gambling skills.

After making it to the final table in a Vegas poker tournament, he told People, “It was fun. It’s just, like, a game I could become better at.”

Good luck.