Raj takes the microphone as he, Wolowitz and Sheldon play some Red Hot Chili Peppers in the video game, Rock Band. Raj kind of sounds like a dying cat but we loved his performance.
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Sheldon and Mrs. Hofstadter (Christine Baranski) decided to perform a little duet in Rock Band to some Journey. Watching them sing and dance was priceless.
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Mrs. Hofstadter goes with her son Leonard to work and meets all the guys at lunch. She quickly analyzes each one of them.
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Mrs. Hofstadter (guest star Christine Baranski) meets Penny on the way up to Leonard's apartment and has no problem analyzing her and figuring out all her father issues.
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After some much needed tequila shots after Leonard's mother terrorized them, Penny and Leonard share a drunken kiss!
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Leonard and Penny decide to do some shots of tequila and after licking the salt off Penny's neck, Leonard has to go in for the lime.
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A picture of Sheldon and Leonard's mother (Christine Baranski) looking over some brain scans of Sheldon's. The two of them get along frighteningly well.
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The Big Bang Theory Season 2 Episode 15 Quotes

Penny [about his mom]: You can't let her get into your head
Leonard: It's too late for me, my head is her summer house

Mrs. Hofstadter [about Penny]: If you want to have sex with that woman, find out what kind of cologne her father wore
Leonard: Hello mother