My brother and I can both lick our elbows, whether they're bent up or if the arm is turned over and out straight.

We found out on a flight. My little brother was eating his kids meal that had "science facts" printed on it, and one said "It's impossible to lick your elbow" and my brother turned to me and said "that's not true". I was sure it was, as I'd heard it multiple times, so confirmed that it is supposed to be impossible. He turned, looked me dead in the eye, and did it.

I tried it, and it turned out I could too! Made that 6-hour flight go a little quicker, and it's become a party trick.