Two comebacks

No, not sports comebacks. These are replies to someone who has said something critical of you.

1) What they say when they think you are staring at them:

"What are you looking at?"

    What your comeback should be

"Not much!"

2) What they say in response to your previous witty comeback

"Don't get smart with me."

    What your comeback should be

"Well, one of us needs to be smart about this."