Kellan Lutz has every reason to be proud of his body. Seriously, look at that thing.

But the actor admits he was a bit hesitant to bare almost everything for a recent Calvin Klein underwear campaign. The reason?

"Now my nude ass is going to be all over billboards, we'll see what my mother thinks," he joked to Us Weekly about the shoot.

Not only is it true that the Twilight Saga star appears nearly naked (alongside True Blood star Mehcad Brooks, Spanish tennis player Fernando Verdasco and Japanese athlete Hidetoshi Nakata) in the ads... but they'll be officially released in 3D on March 1.

While he might be a bit embarrassed at the next family function, Lutz is the perfect shill for Calvin Klein. Again, just look at the guy's body. And now listen to him talk about the garments.

"You know I've done other fittings where you have to wear underwear and you're kind of uncomfortable because they look funny or it doesn't fit well. That's the difference with Calvin Klein. They fit great, they're snug and they hold everything in and you look good," he said.

Point taken, but let's be real: Kellan would look good in a Snuggie.