Interesting. There is a condition known as bendy bone syndrome. It is rare, but still the most likely cause of your problem. It's basically a genetic order, resulting in a lack of skeletal rigidity, an increased flexibility of the joints and the tendency to flop over and fold up at inopportune moments. Is there a history of bendiness in your family?
Yes, my mother can squeeze
through a cat-flap without breaking
a sweat, and my grandfather was
billed as 'The Amazing
Rubberman' during his circus days
No, not really. I have
an uncle who's bent,
if that's what you
mean?