It’s an old Reddit story. Some sort of “what quirk does your family have, that you didn’t realize was weird” /r/AskReddit thread. Dude’s entire family took shits so massive and solid that they had a butter knife that was designated as the poop knife. If they took a shit too big to fit down the drain, they would use the poop knife to dice it up before flushing. Apparently this was a fairly common occurrence, to the point that they just had it hanging on the bathroom wall for anyone to use.

And then he went to a house party, and had to take a shit. So he walked out and casually asked the host where their poop knife was. Cue a literal record scratch moment, where the music was paused and the entire party turned to go “where is the what?” It was in that moment that the dude realized that normal people don’t have poop knives.