Leonard: My point is, Priya's gone. And it would be much better if no-one else found out about this.
Sheldon: You mean, you want me to keep a secret?
Sheldon: You know I can't keep a secret.
Leonard: You can if you try. Think about it this way, if I were Batman and you were Alfred, you'd keep that secret. Right?
Sheldon: Why do you get to be Batman?
Leonard: Because, well, Batman has the secret.
Sheldon: Well Alfred has secrets too.
Leonard: Like what?
Sheldon: Alfred knows that Barbara Gordon is Batgirl. Which I've now just told to Batman. See, I can't keep a secret.