Stan and Dan was a Muppet segment on Sesame Street, narrated on-screen by human character Gordon. It was the story of two men, Stan (a Green Anything Muppet voiced by Richard Hunt) and Dan (a Fat Blue Anything Muppet voiced by Jim Henson), who were very good friends. Their friendship was such that either did the same things as the other. These included wearing fedoras, sunglasses, and mustaches.
Then one day, Dan decided to do things differently. He chose to grow a beard, acquire a new hat, and get a new guitar as well. However, the choice to do things differently was not lost on Stan, and so he began to imitate Dan in every way (what with a new hat, beard, and guitar).