an eel
Examples
Marriage is like putting your hand into a bag of snakes in the hope of pulling out an eel.
Marrying means, to grasp blindfolded into a sack hoping to find out an eel out of an assembly of snakes.
Talking to you is like -- like talking to an eel!" "No, is it? I've never tried to talk to an eel. Isn't it as waste of time?" "Not such a waste of time as talking to you!
Cover up the pot, there's an eel in it.
If an eel is with fish, he shows his tail; if he is with snakes, he shows his head.
He lords it like an eel in a tub.