bed-o-snakes

A toilet so full that the mound of excrement has crested the rim of the bowl, resembling a bed of snakes.

The porta-john at the race hadn’t been emptied all day. A man went in and then emerged ashen faced, clearly shaken by what he’d witnessed. Next in line was a woman with her young son who was squirming with urgency to use the facilities. The man said, "Lady I’m serious, don’t let that boy go in there, it’s a bed-o-snakes!"