Niles: Fifteen years with Maris, I end up in bed with her lover.
Martin: Gee, I didn't need to hear that!
Niles: No, no, it was an accident. It was pitch dark, I thought he was Maris.
Frasier: It's a natural mistake. What tipped you off?
Niles: The heat from her side of the bed. [they all laugh]