Sheldon runs into a character played by Mayim Bialik on the 5/17/10 episode of The Big Bang Theory. Might she be the one for him?
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You gotta love this guest-starring appearance on The Big Bang Theory: that's former sitcom star Mayim Bialik!
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This is a scene from the 5/17/10 episode of The Big Bang Theory. Yes, that's Mayim Bialik guest-starring in the sitcom.
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The Big Bang Theory Season 3 Episode 23 Quotes

Don't worry about the moon. We set our laser to "stun."

Leonard

Sheldon: I should have brought an umbrella.
Leonard: What for? It's not gonna rain.
Sheldon: I know that, but with skin as fair as mine, moon burn is a real possibility.