Penny gets ready for a showdown with Alicia (Valerie Azlynn) by stepping up her wardrobe and wearing a little dress to compete with her clear superior for the guys' affection.
When Leonard tells Sheldon he needs to use more honey than vinegar on Penny, he tries an experiment where he uses chocolate as positive reinforcement on Penny. Amazing.
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?