Leonard and Penny's date at the start of the season goes well enough, but Penny is concerned that they can't relate to each other. The guys continue to find themselves in new situations, Raj trying to master his mutism with alcohol and Howard starts a relationship with Leslie Winkle.
Tropes in The Big Bang Theory Season Two
- Artistic License – Physics: In the season finale the guys prepare for a research trip to the Arctic, with Sheldon informing Penny that they're all going to the Earth's magnetic north pole. Being a physicist, Sheldon should know that the Earth's geographical north pole is actually its magnetic south pole, and vice versa.
- As Himself: Both George Smoot and Summer Glau, in the same episode.
- Christmas Episode: "The Bath Item Gift Hypothesis"Sheldon: I possess the DNA of Leonard Nimoy???!!!
- Comically Missing the Point: When Penny tells Leonard about Dave Underhill not being smart:Penny: Because a smart guy takes the nude photos of his wife off his cellphone before trying to take nude photos of his girlfriend.Leonard: He tried to take nude photos of you?Penny: That's what you took from that?! The guy is married!
- Cutting the Knot: Sheldon is giving Penny instructions over the phone on how to open a puzzle box where his flash drive is kept. Penny asks if he has any emotional attachment to the box, and when he says no, she simply smashes it open.
- Evil Counterpart: Penny may have this in Alicia. Somewhat deconstructed in that both girls are a bit too similar (see below).
- Moment Killer: Leonard and Penny bonded over their parental issues and ended up in bed. Leonard ended up killing the mood himself by channeling his mother's psychological theories, which severely disturbed Penny.
- "Not So Different" Remark: Penny accuses a new neighbor, Alicia, of using the guys to get stuff and help her. Said neighbor points out that Penny does the same thing.
- One of the Guys: As part of Penny's character development we see her hanging out with the guys a lot more regularly and not just passing them in the stairwell compared to the first season.
- "The Reason You Suck" Speech:
- Leonard tries giving one to Penny regarding her ignorance of his feelings while she was seeing David. This brief bought of courage became moot when it turned out David was married and using Penny, leaving her burned.
- Penny gives one to Howard, who was not getting the hint that she didn't like his advances and was also being discouraged by Leonard.
- Romantic False Lead: Leslie Winkle to Penny, especially so soon after her and Leonard's first date. Dr. Stephanie to a milder degree, as Penny made a valiant showing of being happy for him. On the other side, Penny dating both David and Stuart caused a great deal of jealousy from Leonard because they had many of his similar quirks that Penny claimed to be overwhelmed by.
- Sherlock Scan: Sheldon deducing with whom Leonard is speaking on phone.
- Tomboy: Penny started to be portrayed as more masculine than the guys, including one joke about them sending her to kill spiders in the bathroom. Notably, the first resurgence of her and Leonard's Unresolved Sexual Tension happened while she was wearing an oversized t-shirt and ball cap.
- Unresolved Sexual Tension: The first season Leonard's crush was largely one sided. Once Penny knew about his feelings for her you can see her looking back in return.
- What Happened to the Mouse?: It's never mentioned when or why Leonard and Stephanie broke up. While Leonard did decide to have her move out, he still leaves to sleep with her at the end of the episode which causes the confusion as to what happened with her after that.
