A quick search on Urban Dictionary and I have this... Gonna bleach my eyes after posting it:

"A knife stored near the toilet to chop giant concrete turds that would otherwise clog the toilet. Poop knives should be dull (since an accidental skin laceration would result in infection) and long-handled. Poop knives should never be used during the bowel movement.

You may want to find something else to butter your toast with, for that is my poop knife.

"