Melissa Rauch

Sheldon enters a competition but is annoyed when he finds out that 'Star Trek' actor Wil Wheaton is participating because Wil cancelled his appearance at a sci-fi convention that Sheldon had attended as a child.

An embarrassing secret of Wolowitz's is revealed; Raj and Sheldon get into a war at work.

Penny feels left out when Bernadette shows an interest in science and asks Sheldon to teach her about science. Eventually, she surprises everyone with what she's learned.

Wolowitz is torn between taking things to the next level with Bernadette and pleasing his mother. Meanwhile, Leonard rekindles his relationship with Raj's sister, Priya.

Tensions run high when Bernadette runs into her hulk of an ex-boyfriend at a science conference. Threatened by Bernadette's ex-boyfriend, Wolowitz has an argument with Bernadette and causes chaos.

Sheldon agrees to take part in a short lecture series at the university, but worries that the students don't seem to like him. On Amy's advice, he asks Penny to give him acting lessons so that he can engage with his audience better.