All from Sheldon:

"Yes, it tells us that 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 affects your personality."

"Ah gravity, thou art a heartless bitch."

"I am truly sorry for what happened last night. I take full responsibility and I hope it won't color your opinion of Leonard, who is not only a wonderful guy but also, I hear, a gentle and thorough lover."

"At least now you can retrieve the black box from the twisted smoldering wreckage that was once your fantasy of dating her and analyze the data so that you don't crash into geek mountain again."

"Oh, I'm sorry. Did I insult you? Is your body mass somehow tied into your self worth?"

"No, I'm going to ask him to choose between sex and Halo 3. As far as I know, sex has not been upgraded to include high-def graphics and enhanced weapon systems."

"Well, there's always the possibility that a trash can spontaneously formed around the letter, but Occam's Razor would suggest that someone threw it out."

"I don't guess. As a scientist I reach conclusions based on observation and experimentation. Although, as I'm saying this, it occurs to me that you may have been employing a rhetorical device, rendering my response moot."

"Would you ask Picasso to play Pictionary? Would you ask Noah Webster to play Boggle? Would you ask Jacques Cousteau to play Go Fish?"

"In a Venn diagram, that would be an individual located at the intersection of the sets "no longer want my Time Machine" and "need 800 dollars"."

"One more thing. It's on, bitch."

"Oh, well, this would be one of those circumstances that people unfamiliar with the law of large numbers would call a coincidence."