Little is known about the exact origin of pipi du pipou, and the phrase circulates mainly as a short, shareable soundboard clip rather than from a widely identified film or show. Its appeal comes from the French wording, which sounds cute and musical even to listeners who do not speak the language, while the bathroom meaning adds a cheeky twist. Online, it is passed around for the same reason other nonsense phrases spread: it is brief, easy to recognise, and flexible enough to punctuate jokes, reactions and deliberately immature edits.