I was cleaning out my file drawers and found this joke from about 20 years ago.

A graduate student had a cockroach and set it on a table and told it to jump.  It jumped to the end of the table.

The student picked the cockroach up and pulled off a couple of legs.  Then he set it down on the table and told it to jump again.   It jumped about halfway.

The student picked it up again and pulled off a couple of more legs.  It jumped, but not very far.

The student pulled off the last remaining legs.  He told it to jump, but it did not move.

The graduate student concluded that a cockroach with no legs is deaf.

Twenty years later, I realize my thesis adviser may have been insulting me.