Duck Soup (1933)

The best first date with the brothers, because nothing gets in the way. Groucho's Rufus T. Firefly is handed control of bankrupt Freedonia by the wealthy Mrs. Teasdale and promptly talks the country into war, and Leo McCarey keeps the whole thing to about 70 minutes of insults, sight gags and the famous mirror routine, in which Harpo, dressed as Firefly, poses as his reflection. It flopped at the box office in 1933 and ended the team's Paramount contract, which says more about the mood of the time than the film. It was also Zeppo's last appearance with his brothers, and it entered the National Film Registry in 1990. If this one leaves you cold, the rest probably will too.