Walter Matthau and Jack Lemmon are so good in this hilarious 1968 comedy directed by Gene Saks. Written by Neil Simon, based on his play of the same name. If you're only familiar with the TV show, you must see this movie. Matthau originated the role of Oscar Madison in the original run of the Broadway play; Art Carney was Felix Unger, but turned the movie role down. The film was a big hit.