I just love swimming-related pantsings where the shorts come clean off, and because the target is swimming, they aren't wearing anything else, not even shoes. Left fully nude, head to toe.
In my fantasies, it's a light-hearted prank that accidentally leaves the target stranded naked. Like, he's running after someone with his shorts, but accidentally runs out the wrong door and finds himself locked out naked on the street. Or they're at a river or ocean, and he finds himself swept away by the current until he's stranded naked far from any clothing.
Also in my fantasy: I'm the target of the prank and I'm the one stranded naked.