Duh, his loincloth falls off in the struggle. He's been wearing it pretty low on his hips because Tony can't look at Steve's hipbones and have higher thought at the same time. But that means when he had to throw down with the bear, it got dislodged.

Tony is convinced he was holding it up by sheer willpower and it only fell down cause he was distracted by the bear.

Anyway, he snaps the bear's neck with his bare hands. While naked. There's claw marks on his deltoids, and he's bleeding a little bit and sweating a lot. Tony has to hold himself upright with a nearby tree as all available processing power is directed away from frivolities like standing.

That will be... uh, one dollar twelve cents.