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Dressed as characters from Star Trek: The Next Generation — Howard as a member of the Borg, Raj as Lt. Worf, Leonard as Capt. Jean-Luc Picard, and Sheldon as Lt. Commander Data — the guys run into trouble when their car breaks down on the way to a comic-book convention.
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The Middle Earth Paradigm Part Two
When Penny invites the guys to her Halloween party in season 1, the costumes they wear cause confusion among the guests. Sheldon (as the Doppler Effect) is mistaken for a ''choo choo train,'' it's unclear whether Raj is Thor the Norse God of Thunder or Thor of Marvel's The Avengers, Howard's Robin Hood getup makes him look more like Peter Pan, and Penny's ex-boyfriend teases Leonard (dressed as Frodo from The Lord of the Rings) about being a dwarf. Of course?
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The Middle Earth Paradigm Part One
?that's only after it's decided that they can't all go to Penny's party as The Flash.
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Home from the Renaissance Fair
Leonard, Howard, Sheldon and Raj are in full period costume when they run into Penny and her new boyfriend in the second episode of season 2. Though Leonard explains that the group is arriving home from a Renaissance fair, according to a smug Sheldon, the gathering was ''more of a medieval slash Age of Enlightenment slash any excuse to wear a codpiece fair.''
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After losing a bet to Sheldon's nemesis, Star Trek alum Wil Wheaton, the boys are forced to parade around the comic book store dressed as female superheroes Bat Girl (Howard), Wonder Woman (Sheldon), Super Girl (Leonard), and Cat Woman (Raj) in the season 3 episode, ''The Wheaton Recurrence.''