oh my goodness, there are so many!
Remember, one person's hidden rules are not right or wrong, or better or worse than another's. What matters is that they are unspoken, and trigger discomfort when they are violated, even unwittingly. So making them more explicit might be helpful in situations where we must interact with folks who have different rules than we do.
Perhaps simply understanding that hidden rules exist might disarm some of their triggering potential, and we may decide that when in Rome, we'll actively try to determine the hidden rules and do as the Romans do.
Here are some I've noticed in just the past day or so:
It's rude to interrupt.
Talking over me is the best way to let me know that you have something to say.
Don't ask directly for what you need, just hint at it and let me offer.
Ask me directly for what you need, don't make me guess!
It's no big deal to be 5 or 10 minutes late.
Being prompt is a sign of respect.
Don't start eating until everyone is seated at the table.
What are you waiting for? Eat while it's hot!
When you make plans, you keep them no matter what.
All plans are tentative, and can be cancelled for any reason at any time.
Cancelled plans must be rescheduled immediately.
We'll figure it out as we go along.
Our conversations should be half about me and half about you.
Structured reciprocity feels too repressive.
If you cared, you'd ask me why I am upset.
If you cared, you'd give me my privacy when you see I am upset.
If you respect me, you'll do as I ask.
I'm so glad you respect me enough to say no to my requests.
I am helping you by pointing out the areas where you need improvement.
I will politely look the other way when I see you faltering.
If someone really wants to help you, they will insist after you politely decline their first offer.
No means no, and I won't ask again.
If you don't offer to serve me food and drink, you are not a gracious host.
Because we are so close, my house is your house, so please help yourself to anything.
You should always knock or ring the bell, even if my door is open.
Why are you making me answer the door? Just come on in!
Family should never have to stay in a hotel when they come to visit.
I want to stay in a hotel so my visit doesn't make extra work for you at home.
We split the check each time.
We take turns picking up the check.
We get separate checks because it's embarrassing to haggle over the money.
I am insulted when you offer to pay. Don't you think I can afford to treat you?
And this list is just the tip of the iceberg. I go back to my original assertion that it's nothing short of miraculous that we manage to get along as well as we do.