Chess Pains - S3-E18
Other mistake: When Frasier sets off the fire alarm Daphne comes running from her bedroom at the end of the hall across from Martin's room and Frasier's room. That is incorrect and impossible since Daphne's Room is on the other end of the condo and separated by the balcony. Given the condo layout, it is impossible for Daphne's bedroom to have a door across from Frasier's bedroom.
Answer: Nanny G (Nanette Guzman - played by Laurie Metcaf) has been a children's entertainer for twenty years, and tells Frasier, "Do you know what it's like to play the same character for 20 years?!" The joke is that Kelsey Grammer has been playing Frasier Crane since 1984, when the character first appeared on "Cheers", so Kelsey in real life has been doing just that!
Super Grover ★