Who would win in a fight between a thumb and a big toe?

The big toe is considerably stronger than the thumb however it has limited flexibility and a small grip area making it easy to escape. The big toe (as anyone who has ever walked through a house in the dark can verify) has a large number of nerve endings in it and is very sensitive.

The thumb is reasonably strong but considerably more flexible and due to its lower surface area it can exert a larger amount of pressure and thus inflict more pain.

The big toe would fight bravely but the thumb would win.