In one of the best and most popular I Love Lucy episodes of all, Lucy (Lucille Ball) continues her efforts to convince her visiting friend, Caroline Appleby (Doris Singleton), that she has been hobnobbing with all the big stars during her stay in Hollywood. Taking advantage of Caroline's nearsightedness, Lucy hides Caroline's glasses -- and, with the help of some clever costuming and a collection of celebrity masks, she passes herself off as Gary Cooper, Clark Gable, and Jimmy Durante. Meanwhile, Ricky (Desi Arnaz) and Fred (William Frawley) run across Harpo Marx -- in full costume, having just performed a benefit -- near the Beverly Palms Hotel pool. The boys ask Harpo to pay a visit to Caroline so that she can go home claiming to have met a genuine Hollywood movie star. What Harpo doesn't know is that Lucy, in her zeal to keep up her deception with Caroline, has just donned another disguise -- that of Harpo Marx! This is the episode in which Lucille Ball and Harpo Marx, dressed in identical outfits, brilliantly restage the famous "mirror routine" from the 1933 Marx Brothers film Duck Soup -- and as a bonus, Harpo performs a harp rendition of "Take Me Out to the Ballgame."