Movie Star Moment: Buster Keaton

Buster Keaton as The Groom
in "One Week" (1920)

   "One Week" is the two-reel comedy in which Buster Keaton and his new bride build a house out of a kit. The fact that all the pieces in the kit are misnumbered doesn't stop Buster from building the house. It just results in an unusual house. 
    There's a part of the movie, somewhere in the middle, where shots of Buster working up on the roof are intercut with shots of his wife (Sybil Seely) inside the house taking a bath. You're looking at the girl in the tub when a bar of soap slips out of her hand and lands a few feet away on the floor. The girl could get out of the tub and get it, but then she realizes that the camera's there, and if she gets up, the audience will see her naked. It's one of those physical dilemmas that occur constantly in Keaton's movies, and he solves it in the most practical way possible. A hand (presumably Buster's) appears out of nowhere and covers the lens for a couple of seconds, which is just long enough. When the hand moves away again, the girl's back in the tub with the soap in her hand, her modesty mostly intact. 
    Problem solved. Fourth wall demolished. A gag that still gets a laugh after 100 years. Pure Buster Keaton.