Another Sheldon-Penny moment and this scene contains one of my favourite ever lines from the show. Penny is practicing mixing drinks for her job at the Cheesecake Factory and gets the guys to help her out by acting as mock-customers. Howard orders a "Slippery Nipple" and is barred, while Sheldon orders a diet coke. After being told by Penny to order a cocktail, he replies: "Fine, I'll have a virgin Cuba Libre." A bewildered Penny responds - "That's erm, rum and coke without the rum." "Yes." "So coke." "Yes, and would you make it diet?" Bazinga.