Sheldon and Leonard in “The Irish Pub Formulation”

You know I can't keep a secret!

You can if you try. Think about it this way: if I were Batman and you were Alfred, you'd keep that secret, right?

Why do you get to be Batman?

Because the Batman has the secret.

Alfred has secrets, too!

Like what?

Alfred knows that Barbara Gordon is Batgirl. Which I've now just told to Batman! See, I cannot keep a secret!