It's possible to be over-flexible, to destabilize one's joints.

cf note above about coming at this from a childhood at a dance studio!

And one person's destabilized joints is another person's "look I am best contortionist ever!" Bodies: bitchy like that.

Everything's bad for you if you do it enough.

Especially nothing. *solemn* It's almost like our bodies were hamfistedly designed by evolution to move about in various different ways at various different times!