The phrase comes from Le Dîner de Cons, the 1998 French comedy written and directed by Francis Veber. It is associated with François Pignon, played by Jacques Villeret, an earnest guest whose well-meaning blunders drive much of the film's humour. In French, une boulette is a blunder, so the line works as an instant admission of error. Clips of the delivery later circulated on French soundboards and in short edits, and this longer take remains popular because the stretched reaction makes even a tiny mistake feel theatrically disastrous.