Social conventions you thought everyone knew

[Asuperblyfeauturedroomandexcellentboiledpotatoes]

The thread started by the lady who's father recently died and people turned up to his funeral in joggers got me thinking.
What is something you thought was basic social etiquette, a rule that everyone lived by, that you were shocked/surprised to see someone not following?
Did it make you judge the person? Wonder if maybe you're just old fashioned? Or something else?

I'll start. At work the other day someone said they were leaving early because they had a hospital appointment. A younger colleague said "oh, what for?". It felt very awkward and the colleague said "oh.. you know, just women's stuff".
I always thought that you never ever ask people for details of medical appointments or why they were off or what OP they are having. It's very rude. Same as you don't ask people how much they earn or who they are going to vote for or questions about their sex life or something!
At first I judged but then remembered she was young and maybe noone had told her.

What's surprised you lately?

What do you mean, "just leave the bed made up"? The bed won't have been made up after they got out of it, which means they've gone to the effort of making it up. That may not be what you want, but it's at least making an effort!

Totally disagree- i Like people to ask and always say no leave it

Well I certainly don’t expect children to give up their seats. They can get thrown around the bus. I would stand up for a young child to sit down and some people would consider me elderly.
There are usually separate wheelchair and buggy spaces.

Privacy from what? Bills, council tax, statements are all joint.

OMG this!! It bemuses me how no one seems to think about it - how's anyone to know if a screaming child is in danger/distress if all of them are screaming all the time!

Farting out loud at the table, in front of guests etc. just feels so rude to me

DO you arrive on time or how many minutes earlier is the done thing?

Burping at the table in CHina i think it very polite and a sign you enjoyed the meal...do beg my pardon lol

I think you are supposed to arrive a few minutes late if going to someone's house.

I’m nearly 50 and I give up my seat for children on public transport.

Waiting to cheers before taking a sip
Not clearing the table until everyone has finished eating

Farting out loud is rude full-stop.

Also was anyone else told if it happens by mistake, the correct thing is not to mention it by apologising?

Delightful.

Consideration of others. Completely out the window now in order to get what they want, no matter what.

Politeness too.

Really? Why would you think that? Surely it’s polite to wait until everyone is served.

People wear pyjamas to breakfast in public? Really?

Cheese, or any dairy isn't poisonous to cats! It's not good for them, can go through them because they can't digest the lactose, making them unwell but it's not poison.
You can buy cat milk. They just take out the bit that they can't digest, the lactose.

yes, to breakfast buffets in hotels.
Who gives a crap?

Really? We were always plonked onto my mother's/granny's knee when the bus started to fill up.

Why thank a security guard? Because they didn't catch you?

Sorry but I would hate that. I don’t drive so I’m usually rushing to catch a bus or train. I do see people out if they’re not family. But in our family we just say bye and see ourselves out. If it’s a celebration we say thanks for coming but no waving off.

It's very common though, nearly as bad as going to the shop or doing school run in them.

Different cultures/classes have different manners. Why would you let your food get cold?

Lighten up a little, when did I say I go around feeding cheese to other people's pets? Lol

(Dairy isn't poisonous to cats, most cats are intolerant to it but a tiny amount doesn't harm them.)

I always used to put my children on my knee so someone else could sit down. DS was very slim I sat him on my knee until he was about 9. Nobody seems to do it anymore.