Howard and Raj make it their mission to figure out where Sheldon is headed on The Big Bang Theory. "The 43rd Peculiarity" is the eighth episode of the show's sixth season.
Sheldon: I'll have a diet Coke. Penny: Can you please order a cocktail? I need to practice mixing drinks. Sheldon: Fine... I'll have a virgin Cuba Libre. Penny: That's... rum and Coke without the rum. Sheldon: Yes, and would you make it diet?