Sheldon tries to intervene when he discovers a secret about Penny and Leonard on The Big Bang Theory. "The Decoupling Fluctuation" is the second episode of the show's sixth season.
Who would guess that Penny and Leonard's Valentine's day wouldn't go as planned on The Big Bang Theory? "The Tangilble Affection of Proof" is the 16th 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?