The Big Bang Theory:
Penny: What do you want to drink?
Sheldon: Diet coke.
Penny: Can you order a cocktail? I need to practice mixing drinks.
Sheldon: Okay, I'll have a Vigrin Cuba Libre, minus the rum.
Penny: That's rum and coke... minus the rum...
Sheldon: Yes.
Penny: ...So coke?
Sheldon: Yes. Could you make it diet?