Give me an example of how to politely call someone stupid.

I like the southern way of addressing that.

"Bless your heart" where I'm from

I'd just say that, "I would agree with you, but we'd both be wrong!".

"Well bless your heart"

I'm an Italian girl if someone is stunad you have to tell them

One of us is impressed with your intellect!

that is a good one

You get them to say it 😅

I really rather regret to have to inform you that you're entirely lacking in smartness 😙

looks like you haven't watered your wisdom tree in quite a while

"Koo-Koo for Cocoa Puffs" ~Charles Barkley~

You’re not the brightest bulb in the socket are you

🤔

🤦