Dislocating my shoulder on command
Remembering absolutely useless shit.
When I was in high school I read some novel in which the woman admires the hero because he has a habit of throwing his keys over his shoulder and catching them behind his back. I practiced and learned to do it pretty easily. But I never had the confidence to do it casually in front of women. Or anyone really.
Plugging in the USB key at first try
Cracking my joints.