Sexy Antonio Sabato, Jr. is about to be exposed -- literally. The former Calvin Klein model is posing in his underwear again, only this time the father of two is doing a daring American Gigolo photo shoot for the men's gay lifestyle magazine, Instinct, and only "Extra" went behind the scenes.

"This is new to me, so we'll see," Antonio said of posing for the magazine. Sabato, Jr., who usually plays a lady killer in his films, also changes it up in his new risqué black comedy, "Testosterone." The actor steps out of character as a gay man who dumps his lover in the film, and his role includes two onscreen firsts: a gay kiss and a full-frontal nude scene.

"It was a really interesting experience for me," he said. "You want to reinvent yourself and this was a chance to do that, so I couldn't say no to it."

Antonio also jumped at the chance to show us his newly pierced ears: "I just got my earrings done. If Harrison Ford does it, I want to do it."

So does the big actor still wear his Calvin's? "All the time," Sabato, Jr. insisted. "There's no underwear without Calvin Klein."

Check out Antonio's incredible photo spread in Instinct magazine, on sale now.