Jogging Curls - get a DB in each hand like you're going to do curls. Do with your hands what you do with them when you jog at a decent pace. Including the swinging motion that your chest makes. Only, don't move your legs. Again, doing this to Britney completely sexy-fies the movement.
I hate to tell you, but I think that's a real exercise. My friend at work used to do these as part of sprint training. Hold DBs hammer curl style, and then "run" without using your legs. He said it was to help them build up their upper body and torso muscles for sprints without having to sprint, and to train that arm swing. We just talked about these today.
So I wonder if that guy doing them at your gym has a track and field background...
I can see the point if you're a sprinter although only thing I think it would really do is train the 'arm pump'. I think the effects to the upper body/torso strength would be limited if at all. It sounds like the same kind of theory behind ankle weights, too, or boxers shadow boxing with DB's in their hands.
It's funny that it's actually a legitimate thing to do, though. No chance this guy's a sprinter, if he was, losing about 20-30lbs of fat would be the first thing he could do to make him faster... It's actually the same guy that does the 'lat hip humpers'. He has a whole catelogue of strange exercises.
The crouching tiger guy is different though, and in a class of his own. He actually works incredibly hard. He just uses some strange exercises.