I have posted in the past about a SIL coming in the front door, opening the fridge behind me as I worked in the kitchen, pulling out a beer, popping the top, taking a swig, and THEN saying "Hi!" to let me know that she was not the DH or DD.............
The six-pack had been purchased for the weekend football game for the three of them (DH, BIL, and his wife) to share at our house - and we were just staying ahead of expenses on earnings. My substitute teacher money could not be depended on for bills - but did manage to stretch to the occasional "extra" - like a new winter coat, beer, or a steak instead of hamburger.................
She got her beer Sunday, the BIL got one, and DH drank one - there wasn't enough beer left to offer a second round (because of her opening one without announcing that there was a "guest" in the house).
I don't drink beer - so it was "no skin off my nose" except figuratively reminding me that our hospitality was that straitened at the time.