"Have you got enough money?"
A sweep of the eyes up to the ceiling.
They put on that weary tone of voice – that long-suffering, quietly desperate voice that means your stupidity has driven them to the edge. It's often accompanied by a deep, heartfelt sigh. (Because, after all, they are having to put up with the burden of your silliness on a daily basis.)
You may think it's reasonable to ask if they've got gloves as icy winds sweep across Britain. You may think it's a good idea to check they've remembered their coursework/mobile/travel card/lunch.
(Because, er, they often forget them.)
But to them, you're fussing. You're flapping around like a demented pigeon. You're causing all sorts of unnecessary panic. They don't need this kind of intervention. They know best.
Which is why they're talking to you as if you have very little brain.
What you can't do, when faced with this assumption of superiority, is to get all cross. This is because: a) it's not really directed at you personally – it's a general swipe at everyone who tells them what to do and how to behave, b) they don't realise they're doing it, and c) any kind of row will result in both parties (i.e. not just you, but them, too) feeling hurt and misunderstood.
I have found it works best to bite your tongue. (Least said, soonest mended.)
Alternatively, if you're feeling creative, play the role they've assigned to you, and act the part of some vague and dotty old dear who's hopelessly out of touch with the modern world – a Miss Marple without any of the detective skills.
"What time will you be home?" you say.
Your teenager sighs deeply. "I've already told you."
(She didn't. But don't argue.)
"I'm sure you did," you say humbly. "But I've completely forgotten what you said."
A second, much deeper sigh. (How much more does she have to put up with?) "The usual time."
"Oh, good," you say brightly. "I'll see you later, then."
If you were in Hollywood, you'd get an Oscar.