I experienced a poop knife in real life. In Boy Scouts, there’s a thing where you can go sail in a boat off the coast of Florida for a week. When the captain explained the rules, he talked about a stash of disposable knives in the head (bathroom).

Basically, he had issues with kids trying to hold their poops until they got to the mid-week stop on shore. They wouldn’t make it and ended up clogging the 30 foot boat’s plumbing with their product, so he explained that if we took a big enough shit we had to cut it up before flushing.