Tall, thin man Bud Abbott (1895–1974) and short, fat man Lou Costello (1906–1959) worked together for Universal Pictures between 1939 and 1956 after a career in comic theater and radio (see entry under 1920s—TV and Radio in volume 2). Throughout the 1940s, but especially during the years of World War II (1939–45), they were Hollywood's top comedy act. At their peak, the duo made four films a year, specializing in silly voices and overacting. In their best early films, a simple misunderstanding soon leads to hilarious situations.

The most popular misunderstanding is found in the classic "Who's on First" bit, which was first a radio routine, and then a scene from The Naughty Nineties (1945). In it, Abbott continuously frustrates Costello by trying to explain to him the odd nicknames of players on a baseball team: "Who's" on first, "What's" on second, and "I Don't Know's" on third. Costello: "Who's...