 Knock (original title "Knock") is a French comedy film from 1951, directed by Guy Lefranc, written by Georges Neveux, and starring by Louis Jouvet.It also features an uncredited appearance by Louis de Funès.The movie is based on the 1923 theatre play "Knock ou le Triomphe de la médecine" ("Knock or The Triumph of Medicine") by Jules Romains.