Two And A Half Men: Season 4, Episode 16

4 - 16: Young People Have Phlegm Too

Charlie's young, hot girlfriend takes him to a new club. She invites Alan to meet one of her friends but the men are shocked to learn that they are considered "old." A health scare has Charlie feeling depressed, but Alan has an idea to cheer him up. Title quotation from: Charlie, to Alan, after he coughs up phlegm.