27. "A Little Kiss, Part 1" (Season 5, Episode 1)
Megan throws Don a surprise birthday party, complete with a sultry dance to "Zou Bisou Bisou." It's strange how Don and Betty, two of the rottenest spouses in TV history, luck into rebound marriages with the two sanest people on the show. (Henry and Megan really should have married each other.) Megan also decides to get Don's attention by cleaning the carpet in her lingerie. Shockingly, this plan works. No wonder we all got our delusional hopes up for this marriage.
Joan/Lane watch: A touching moment for us long-suffering Joan/Lane shippers, as Joan weeps in his office over her post-partum blues, and Lane cheers her up with a burlesque dance of his own.
Best line: "The only thing worse than not getting what you want is somebody else getting it."—Roger Sterling