Mort Sahl was a comedian, and a friend of Lenny Bruce. Archive footage of one of his records can be heard in an episode of The Marvelous Mrs. Maisel.
S1E1 - Susie tells a story about seeing Mort Sahl perform and knowing that he had the goods.
S1E5 - Midge listens to one of his records.
S2E5 - Susie mentions that Mort is playing the Copa.