The Odd Couple is a comic gem. One the funniest script ever committed to celluloid - exceeded only by Strangelove, Spinal Tap and Lebowski! Lemmon and Matthau are best friends: obsessive compulsive Felix and sloppy, irresponsible Oscar. Oscar's wife has already left him because he is impossible to live with due to his irresponsible attitude. Felix's wife leaves him at the start of the movie, and after an aborted suicide attempt he moves in with poker buddy Oscar. Thats when the fun begins.
The entire script is brilliant and filled with brilliant one-liners. You are probably already familiar with the "F.U." joke but it still works brilliantly due to Matthau's comic timing.
My favorite moments are when Lemmon tries to clear his sinus in the diner and when the Pigeon sisters are being charmed by a very suave Matthau and Lemmon is totally out of his element. This one requires repeat viewings!