I'd like to give you a going away present. First, do your part.
This is an excellent time for him to become a missing person.
Whom am I calling 'stupid'? Good question. What is your name?
He has an inferiority complex -- and it's fully justified.
He should do some soul-searching. He might just find one.
I don't know what makes him so dumb, but it really works!
A sharp tongue does not mean that you have a keen mind.
Brains aren't everything. In your case, they're nothing!
Please, keep talking. I always yawn when I'm interested.
Sit down, give your mind a rest. It obviously needs it.