"The Euclid Alternative"

When Leonard needs to work the graveyard timeslot to gain access to the lasers for his experiment, Sheldon loses his ride to the university.

"The Griffin Equivalency"

Raj is included in People's "30 under 30 to watch" list, prompting the rest of the group to be jealous.

"The Barbarian Sublimation"

When Penny locks herself out of the apartment, she comes to hang out with Sheldon in his as he plays Age of Conan. Penny, frustrated by her recent failures in life soon plays and becomes addicted to Conan.

"The Codpiece Topology"

The guys return from the Renaissance fair and see Penny has already moved on to a new guy, Eric (Travis Schuldt), prompting Leonard to pursue a relationship with prior fling Leslie Winkle.

"The Bad Fish Paradigm"

Penny and Leonard return from their date from the end of season one and Leonard finds Howard and Raj spying on them via webcam.

"The Tangerine Factor"

Penny breaks up with her boyfriend after he posted intimate details about her on his blog. Leonard tries to comfort her but accidentally sends her back into the arms of her boyfriend.

"The Peanut Reaction"

When the boys go to eat at Penny's restaurant, she learns Leonard has never had a birthday before. She decides to throw him a surprise party and blackmails Leonard into helping.

"The Porkchop Indeterminacy"

The guys meet Sheldon's extremely attractive twin sister Missy (Courtney Henggeler) who is in town for a wedding.

"The Nerdvana Annihilation"

Leonard buys a replica time machine online from the 1960 film The Time Machine and ends up splitting it with the guys.

"The Bat Jar Conjecture"

The guys compete in a physics bowl after the previous contestants dropped out to form a barbershop quartet. When Sheldon's showboating becomes too much for them, they kick him off the team.

TBBT Quotes

Penny: Here's a question-- as an alien pretending to be human, are you planning to engage in any post-prom mating rituals with Amy?
Sheldon: There are post-prom mating rituals?
Penny: Not always. Unless your date drives a van with an air mattress, then always.
Sheldon: Well, if it's part of the prom experience, then I'm open to it.
Penny: You're kidding.
Sheldon: I may be an alien, but I have urges.If Amy wants to copulate by firing her eggs into space, well, then, I will happily catch them with the reproductive sac on my upper flermin. I'm not the best at reading facial cues, but I can see that you're a little turned on.

Penny: Hey, Sheldon, did you change your Wi-Fi password again?
Sheldon: Yes, it's "Penny, get your own Wi-Fi." No spaces.