Exxon Valdez poo
When it seems like you've wiped your ass a hundred times and the toilet paper is still covered in poo. Reference to the huge oil spill in Alaska from the ship Exxon Valdez.
I'm taking an Exxon Valdez poo. I just keep wiping and wiping, and it just keeps coming and coming. Oh well, I guess I'll just sit here and let it dry.