No offence, but I don't think the example provided is witty or intelligent. I was expecting an Oscar Wilde type witticism.

I have asked "Were you born that stupid or did it take effort" ...
Usually in response to some bigoted remark.

When some rich turd gets on my nerves i ask why is there only one letter difference from affluent to effluent?

Your dad wiped the best of you on the curtain. ..

The best if you dribbled down your mum's thighs

And to think you were the sperm that won ....

Sorry, one more:

"I don’t want to talk to you no more, you empty-headed animal food trough wiper. I fart in your general direction! Your mother was a hamster and your father smelt of elderberries!"
~ The French Taunter

To be honest, anything the French Taunter says is brilliant.

I'm still partial to this one after all these years:
""You pompous, stuck-up, snot-nosed, English, giant, twerp, scumbag, fuck-face, dickhead, asshole."
Otto from A Fish Called Wanda

"I may be drunk, Miss, but in the morning I will be sober and you will still be ugly."
~ Winston Churchhill

I try not to insult people unless they ask for it.
Then I'm more direct....'go fuck yourself ' gets the point across.
Say what you mean and mean what you say.

You, sir/madam, are a waste of protoplasm that could have gone toward a perfectly good rottweiler.

Does your arse get jealous of the shit that comes out of your mouth?

Your mum should have swallowed you.

If you're going to be two faced, could you at least make one attractive?

I still like Churchill's reply to a woman who said he was drunk, "My dear, you're ugly, but in the morning I'll be sober, and you'll still be ugly."

If it wasn't for your face you'd be pretty ....

Get a brian, moran!

The Funny Times (which I recommend as it helps give some relief to these times) has a T-shirt that says "The universe is made of Protons, Neutrons, Electrons and Morons".

I throw underhanded insults at people all the time hahahaha