26. "Waldorf Stories" (Season 4, Episode 6)
A flashback to the Fifties: Roger meets Don in a fur store and gains a new best friend, i.e. an even more devious shark than he is. Meanwhile, in 1965, the Clio Awards inspire everybody to drink themselves into a Glo-Coated stupor, until Don wakes up to a few nasty surprises. Gentlemen, let's pace ourselves.
Best line: "You've crossed the border from lubricated to morose. Good night."—Joan Holloway Harris