Credit: jack-rs-chris-primo/

Under-wow! Ashton Kutcher exposed his underwear (and adorable assets!) after wiping out on a bike at a motocross camp near L.A., on Thursday, May 22. 

Mila Kunis' fiance, 36, wearing a basic white T-shirt, revealed a mild injury on his tummy. The actor lifted his shirt, dropped his pants to his ankles, and stood around in a pair of tiny navy Calvin Klein boxer briefs during the outfit swap.

Smiling during his panty party, Kutcher turned around and gave photographers a full view of his toned legs and tight rear end! See more photos of Ashton's accident on

Kutcher actually has prior experience modeling and stripping down to his skivvies during his college days. The Iowa native won a modeling contest, and eventually went on to pose in his briefs for Abercrombie & Fitch in 1998. That same year, he starred on That '70s Show, where he met his longtime secret crush Kunis.

The Two and a Half Men actor maintains his muscular physique as a Jiu-Jitsu student. He's also been cutting back on the drinks recently, now that his fiancee—pregnant with their first child—cannot indulge in drinks. (Kunis, who was announced as the face of Jim Beam whiskey in January, once called red wine her "bestie.") In support of his love, a source told Us Weekly that Kutcher has been drinking only in moderation.

Otherwise, the adorable parents-to-be have been photographed getting handsy and preparing for parenthood.

Kutcher and Kunis purchased a new home last month from former MTV CEO Tom Freston in the same gated community as Nicole Kidman and Cameron Diaz. The price tag of $10.2 million includes 3 bedrooms, pool, veranda, and vegetable garden. They plan to move after the baby's born!