Howard and Raj make it their mission to figure out where Sheldon is headed on The Big Bang Theory. "The 43rd Peculiarity" is the eighth episode of the show's sixth season.
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The Big Bang Theory Season 6 Episode 8 Quotes

Leonard: Who you talking to?
Penny: Just this guy I met at school.
Leonard: We're still dating, right?

Howard: Do you expect me to build this?
Sheldon: I expect you to wipe the pudding off your chin. Gentlemen.