1. The Pilot (Season 1, Episode 1): Sheldon and Leonard meet Penny and become friends, while Raj and Howard try to impress women at a comic book store.
2. The Middle Earth Paradigm (Season 1, Episode 11): The guys argue about the morality of downloading TV episodes illegally, while Penny teaches Sheldon how to dance.
3. The Nerdvana Annihilation (Season 2, Episode 17): The guys find themselves in a battle of wills with a group of Trekkies when they try to attend a Star Wars convention.
4. The Dead Hooker Juxtaposition (Season 3, Episode 3): Sheldon and Leonard are arrested after a misunderstanding involving a body in their apartment.
5. The Gothowitz Deviation (Season 3, Episode 14): Sheldon and Penny go on a date to see a movie about space, while Leonard, Raj, and Howard play laser tag.
6. The Pirate Solution (Season 4, Episode 4): The guys compete to see who can solve a physics problem first, while Penny tries to sell cosmetics to Leonard's mother.
7. The Bat Jar Conjecture (Season 5, Episode 10): Sheldon and his friends play a game of Dungeons and Dragons, while Penny helps Leonard prepare for a job interview.
8. The Hawking Excitation (Season 5, Episode 21): Sheldon and Amy attend a lecture by Stephen Hawking, while Penny and Bernadette compete to see who can make a better dessert.
9. The Date Night Variable (Season 8, Episode 9): Sheldon and Amy agree to go on a double date with Leonard and Penny, while Raj and Howard try to find dates of their own.
10. The Conjugal Conjecture (Season 11, Episode 24): Sheldon and Amy consider getting married, while Leonard and Penny plan their wedding.