Did you forget that Frasier is a spinoff of NBC's hit show Cheers? An upcoming episode — titled "Cheerful Goodbyes" — will school you in sitcom history with guest stars from Dr. Crane's fave Boston bar, TV Guide Online has learned. The plot has Frasier (Kelsey Grammer) visiting Beantown to convince Cliff (John Ratzenberger) not to retire and move away — much to the dismay of Carla (Rhea Perlman) and Norm (George Wendt).