Sheldon has made some of the best quotes ever imo.
"Anyway, the local cuisine was a little more sausage-based than I'm used to and the result was an internal blitzkrieg with my lower intestine playing the part of Czechoslovakia."
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Sheldon: But returning to your key conundrum, perhaps you should call a locksmith and have him open the door for you.
Penny: I did. He said he'll get here when he gets here.
Sheldon: And you're frustrated because he phrased his reply in the form of a meaningless tautology?
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Sheldon to Penny: And on a different - but not unrelated - topic, based on your current efforts to buoy my spirits, do you truly believe that you were ever fit to be a cheer leader?