The line comes from the 1990 Christmas comedy Home Alone, where Fuller McCallister is Kevin's younger cousin, played by Kieran Culkin. In the crowded house before the Paris trip, Fuller is warned about drinking Pepsi because he is known to wet the bed. The scene became part of the film's enduring holiday popularity, repeated every December and clipped for memes the rest of the year. Its specific warning about one drink and one character makes it more memorable than a generic soda joke.