You're walking casually down the street at night when you suddenly step on a manhole, which was loose! Causing it to flip and have you fall down inside.

You land inside a tunnel system and you look around and see dark cobblestone walls and moss, you continue further into the sewer.

You find an open area and to your shock, you see a large snake, at least two feet in girth and maybe 30 feet long. It's laying down facing away from you, with a girls body attached where the head should be.