Sentence Usage – How to Express Condolences in American English

I'm not sure that in modern usage of english that we refer to class directly in this way - people tend to reference the attributes that go with being in an upper-class environment, rather than referring to the class itself.

For example, in the scenario you have provided, one might say:

• Have some etiquette!
• Show/have a little decorum.
• Show some manners.
• Show some respect.

...or variations thereof, to request that a friend act in a manner more appropriate to the social situation.

You can also take the opposite view, for example:

• Don't be vulgar.
• Don't be crass.
• Don't be rude.

...and so on.

The closest I can think of that references the social class of that person would be

• show a little class.

...but even then, the reference is indirect.

I think the easiest way to phrase this would be "I stayed with". For instance, if you shared a room with your father at a hotel, you can say "I stayed with my dad at the hotel" or "I stayed in a room with my dad". "I shared a room with my father" is also pretty unambiguously platonic.The details of who slept in what bed are probably not necessary to get your point across. Mentioning or alluding to the action of "sleeping" is what starts to move things into that gray area of possible euphemisms. But to simply say you were sharing a room, or staying in the same room, implies that sleeping was involved without implying that anything sexual occurred.