I don't know much about biology, but I imagine that if your legs were very lightweight and bumpy, and you pressed them firmly against each other, they would pro

I don't know much about biology, but I imagine that if your legs were very lightweight and bumpy, and you pressed them firmly against each other, they would probably stick together pretty well, and so if you tried to move them both in the same direction, but with differing amounts of force, they'd probably stay together and therefore press down in sync.