I was watching this show about moray eels a couple weeks ago, and this guy was talking about how moray eels have a second set of jaws in their throats that, when the first mouth has a grip on its prey, the second set of jaws (complete with sharp teeth) dart out to grab it and pull it down into the back of the throat.
and I was like, "w/e, I already knew this. It's creepy, but you know. eels."
BUT THEN this guy started hand feeding one AND IT GOT HIS THUMB. He started to panic, but then that second set of jaws just GRABBED IT and you could hear the socket pop and then his thumb was GONE. omg. I saw this so long ago, but I haven't been able to forget it.