The line comes from the 1989 comedy National Lampoon's Christmas Vacation, starring Chevy Chase as Clark Griswold. Randy Quaid's Cousin Eddie arrives uninvited for Christmas and is later seen emptying his RV toilet in the street, greeting Clark with the explanation that it was full. The scene became one of the film's most quoted moments and a staple of holiday replays, merchandise and memes. Online, the short audio is reused far beyond Christmas as a shorthand reaction for septic tanks, portable toilets and any container that can hold no more.