I am pretty sure I am doublejointed. I will go to a chiropractor at my gym soon to be sure (they gave me one free visit, yay). If I pull hard enough when i stretch I can feel something slide out of the socket. Both in my shoulders and in my hips.
This would be great if I wanted to be a circus freak but I need to do things such as pullups. And when I hang relaxed from a bar in a pullup position I feel my left shoulder pop out a little and it hurts a bit and feels unnatural. It isn't a full dislocation though, as it doesn't hurt much when I stop.
If I lay down and pull one of my knees towards my chest, I can make my hip pop and I feel something in there totally shift to another spot. And it feels weird. There are other occasions when my hips pop as well and it always feels strange and I feel unstable for a moment.
ugh I wish I had normal joints