Penny: If you were to die this evening with no opportunity to communicate with anyone, what would you most regret not having told someone?
Sheldon: So it would be today? Huh. Well, I suppose there's something satisfying about dying on my birthday.
Penny: Today's your birthday?
Penny: Well that's always been a secret. Not even Amy knows.
Sheldon: Well, I don't enjoy presents. And the thought of people jumping out and yelling surprise fills me with more dread than the words "George Lucas Director's Cut.