Sheldon: You participate in the mass cultural delusion that the sun's apparent position relative to arbitrarily defined constellations at the time of your birth somehow effects your personality.
Sheldon: I'm not crazy. My mother had me tested.
Sheldon: You have about as much chance of going out with Penny as the Hubble Telescope has of finding that at the center of each black hole there's a little man with a flashlight trying to find the circuit breaker.
Penny: Can you help me? I was writing an email and the A key got stuck. Now it's just going "Aaaaaaa."
Sheldon: Coffee is out of the question. When I moved to California, I promised my mother that I wouldn't start doing drugs.
Sheldon: Oh, well, this would be one of those circumstances that people unfamiliar with the law of large numbers would call a coincidence.
Chosen answer: It does. The variable cleanliness of the cab and the habit of taxi drivers to engage customers in small talk would be too much for Sheldon to handle, and not an option for him.
Captain Defenestrator