Cannibal Crab?

OK...as I was watching yet another episode of SpongeBob SquarePants the other day, something dawned on me. 

What exactly is a Crabby Patty? 

I assume that it's like a crab cake, but served up like a hamburger on a bun....with cheese, if you so choose 

So if that is the case....then doesn't that beg the question....Why is a Crab selling Crabby Pattys?  Isn't that like Crab Cannibalism? 

That would be like Kermit selling Frog Legs for Doc Hopper! 

It's just wrong .