Arthur Ewing and His Musical Mice
From the "Sex and Violence" episode (5 October 1969) of legendary BBC sketch comedy show Monty Python's Flying Circus. This madman has trained mice to squeak at selected musical pitches, so that they can squeak tunes when "played" in the proper order. Unfortunately for the mice, "playing" means "hitting with large wooden mallets." He's allegedly playing "The Bells of St. Mary's," but it sounds uncannily like someone killing mice with a mallet. He is roundly castigated by the horrified audience and hauled off by the floor manager. Played by Terry Jones.
This gag was later stolen by the Muppets for The Amazing Marvin Suggs and his Muppaphone. Python Terry Gilliam would reuse the joke (with some modifications) in The Adventures of Baron Munchausen.