I'm double jointed in both shoulders. When I was younger, I could clasp my hands together in front of me, and keeping them clasped, I could 'step through' my arms, bring them up behind me, then over my head to the front again, always keeping my hands clasped together. I remember kids in elementary school saying 'Ooo gross! Do it again!'
I also used to have people stand behind me and pull my elbows together behind my back to where they would touch, and it didn't hurt a bit!
