Today in "embarrassing things celebrities have done so you don't have to," here is Armie Hammer with a public service announcement about proper photographic composition.

It goes like this: When you're photographing things while naked, you may be inadvertently photographing yourself while naked, too, depending on where you are standing.

This is a lesson Armie learned the hard way, as he explained during an appearance last night (July 28) on "Jimmy Kimmel Live."

Basically, Armie is making the rounds to promote "The Man from U.N.C.L.E.," and he wanted to look his best -- so before he hit the latenight circuit, he went to a salon for a quick haircut. But when the actor whipped out his phone to show the stylist pictures of his kids, he also unwittingly whipped out pictures of his fully naked body, which was reflected in the mirror that he'd been standing in front of at the time.

Fortunately, the stylist was either too polite or too clueless to say anything about Armie's, um, hammer.

But for the rest of us, it's a great cautionary tale: If a picture-perfect moment is happening and you don't have time to grab some pants, make sure you aim the camera at a non-reflective surface.