My parents threw me a semi formal party (brunch, champagne, etc.) to celebrate my master's graduation. This was at their home. I was in my 30s at the time, and didn't live with them. A fellow graduate came to the party, then said to me halfway through, "I'm tired. I'm going to go take a quick nap." I assumed she meant she needed to leave early. Instead, she went up into my parent's house, found a bedroom, and lay down for a nap.
She'd never met my parents before, she'd never been in their home before, she knew I didn't live there, and we had only been friends for the two years of our graduate program. My sister went upstairs for something, discovered her and assumed she must have been sick. When she tried to wake her to see if she needed an ambulance, the friend just said, "Oh, I just need some more time to sleep."
Just the oddest thing. I didn't even know how to address it, so I never did.