The Big Bang Theory, Season 1

Sheldon:
I'm uncomfortable having been included in your lie to Penny.

Leonard:
What was I supposed to say?

Sheldon:
You could have told her the truth.

Leonard:
That would have hurt her feelings.

Sheldon:
Is that a relevant factor?

Leonard:
Yes.

Sheldon:
Then I suppose you could have agreed to go.

Leonard:
And what would I have said afterwards?

Sheldon:
I would suggest something to the effect of, "Singing is neither an appropriate vocation nor avocation for you, and if you disagree, I'd recommend you have a CAT scan to look for a tumor pressing on the cognitive processing centers of your brain.

Leonard:
I couldn't say that. I would have to say, "You were terrific and I can't wait to hear you sing again."

Sheldon:
Why?

Leonard:
That's the social protocol. It's what you do when you have a friend who's proud of something they really suck at.

Sheldon:
I was not aware of that.

Leonard:
Now you are.

Sheldon:
Oh. Alright. Leonard?

Leonard:
Yes?

Sheldon:
When we played chess earlier, you were terrific, and I can't wait to play you again.