No matter how drunk someone is, I can't imagine it would be easy to insert an eel up their ass.
Eeels are incredibly strong. I remember extracting an oil barrel from a swamp when I was a ten year old and as the rusty brownish water poured out a suitably aggravated eel - it was
really pissed at being evicted - came with it. I had pulled the oil barrel on land quite some bit, so the eel was crawling over land, it wasn't more than 2 1/2 foot I'd say, maybe 3, but I had no chance holding it in place, it was way too muscular for me back then. And it wasn't slippery and slimy either, rather leathery in fact, its sheer muscle force reminded me of a constrictor snake (which, btw, can exert pressure on a rib cage similar to a full-size train resting on it, you die not from suffocation or because your rib cage breaks, you die because the sheer exerted pressure keeps your heart from being able to pump anymore).
What I'm saying is: Anus muscle versus eel muscle, the outcome is pretty clear.
Uwe