Thought this was somewhat interesting (though by no means earth-shattering)...
Just noticed this while watching taped episodes. There are two episodes in which Fry sticks his hand through a "hole" in his abdomin and wiggles his fingers on the other side.
First one was when Fry first logged on to the internet in the episode where Leela meets Althazar (the "last male cyclops").
The second one was in one of Leela's coma-induced dream sequences in the episode where they collect honey from space bees.