Penny breaks up with her boyfriend, and Leonard comforts her. After he asks her out on a date, both of them turn to Sheldon for advice. Also, Howard teaches Sheldon “Mandarin” so he can complain about his “not so tangerine-Tangerine Chicken”!

Penny finds out that Leonard has never had a birthday party, then she decides to throw one for him. Unfortunately, things don’t go as planned and Howard ends up in the emergency room.

Sheldon’s attractive twin sister “Missy” comes over to visit, and the guys end up fighting over her. Sheldon ends up trying to be so protective of her, much to her displeasure.

Leonard buys a replica time machine online. As the boys move it to the apartment, they make Penny late for work, by accident, causing her to lash out at Leonard for his nerdy ways. Upset, Leonard gets rid of all his “nerdmabelia” and the guys try to convince him not to.

The guys decided to compete in a physics bowl, then they find out that Sheldon is showboating too much, and kick him off the team. Upset, Sheldon decides to form his own team to compete against them!

Leonard and Sheldon look for a way to derail a fifteen year old physics prodigy’s research.

When Sheldon gets sick, the guys what is in the store and avoid him, leaving Penny to nurse the world’s worst patient back to health.

Leonard lies to avoid seeing Penny’s perform, after he hears her singing. Then Sheldon takes it one step further with a more elaborate lie which leads to the appearance of his non-existent cousin!

When Leonard and Sheldon are invited to present their findings at a physics conference, Sheldon refuses! But when Penny steps in to mediate, it only deepens the rift between both of them.

Raj’s parents want him to go out with another woman, who is also from India with the hopes of initiating a pre-arranged marriage. But it turns out that his Indian date have more in common with Sheldon.