How do you say, "You don't know the fuck you're talking about" but in a nice way?

Ask them a trail of investigative questions to assert your knowledge but also pretend you don’t know anything as well. That way you are selling your problem solving not just your knowledge. Some people take offense to it but they can go eat a dick honestly.

Really? I've been told it's XYZ, not ABC. Can you doublecheck?

Listen here noob i was there when the rules were written.......

“Help me understand how you think.”

"you are a fucking idiot and you don't understand a shit, no offense"

The "no offense" will do the job and you'll appear perfectly nice and polite

Excuse me honeybee, but you don't know the fuck you're talking about, sweet sugar cube.

That’s not how it works, that’s not how anything works you dipshit.

"that is not your core competence, isn't it?"