Dear Laura,
A crab pinched me! And it won't let go. It's currently dangling off my thumb, impeding my ability to eat Crobsters.
- Clipped Bondi
Dear Clipped Bondi,
Crabs, although they have vicious pincers, do not usually actively seek conflict. You may have gotten too close for comfort, and so it reacted in the only way it knows. Perhaps you should fast, so that your thumb isn't quite so tasty. In the meantime, with your other paw, try tempting the crab with a piece of detrius. If it will not be tempted, wait a while. In a few days either the crab or your paw will drop off. And look on the plus side! Like Pinocchio has Jiminy Cricket, you have a crab. Why don't you give it a name? 
- Laura