There's an old story about Groucho Marx. One day, when the Marx Brothers were still primarily a stage act, he was too ill to perform. Rather than cancel the show, he told little brother Zeppo, "Just put on the glasses, paint on the moustache, and be me. You know the act. No one will know the difference."
So Zeppo takes the stage, and no one notices he's not the real Groucho, who keeps reporting in sick. Then, one night, Zeppo hears a familiar laugh from one of the boxes – it was Julius Henry Marx, the "real" Groucho. Of course, Zeppo asked him why he was in the seats, and not on stage. "Because I've never had a chance to see myself perform," he deadpanned back.