For people that are stupid/have bad grammar:

I'd call you stupid, but with your understanding of English, I doubt you'd even know what that means.

I'm the grammar police and I'd like to inform you that, if you got anything higher than an ungraded in your tests, there was definitely some bribery behind the scenes

Is this Ricegum's long lost relative?

You're a literal diploid.

Ah, so you're an intellectual? Tell me, how much of Rick and Morty do you actually understand? I doubt you even have a grip on the character of Jerry.

For those with an ego:

If I wanted to kill myself, I'd jump from your ego to your IQ.

Ever heard of the Marvel character Ego? He's like you, but less obnoxious and a face people actually want to see.

Your ego is as high as the twin towers. Actually, never mind. They got destroyed just like your terrible argument.

For those with uncreative comebacks:

As this conversation furthers, I'm progressively loosing more brain cells because of how poor your comebacks are.

Oh God... That insult... Oh God... Oh no... Thanos snapped his fingers because of how uncreative... Oh God... Tony, I don't want to go...

I feel sorry for your parents. It must bring them so much pain that they're the first humans to birth a child without a brain.