Witty Insults

I have neither the time nor the crayons to explain this to you.

I'm not an astronomer, but I'm pretty sure that the Earth revolves around the Sun and not you.

I would love to insult you, but I'm afraid I won't do as well as nature did.

I'm not insulting you, I'm describing you.

Light travels faster than sound, this is why some people appear bright before they speak.

Insult: You ruined it.
Comeback: Your ass ruined where your face was supposed to go.

Insult: Fail!
Comeback: Just like your social life

I would say that you are barking up the wrong tree, but that is your natural voice.