My housemates Mum came to stay (in a hotel nearby), we were in our mid twenties, and this was my first proper house rather than living in bedsits.
I had met her before and she'd seemed nice, a bit bonkers but generally friendly, so I was rather taken aback by what happened.
She took us both to a supermarket, one neither of us used as we were both pretty broke. I kept telling her I couldn't afford this supermarket, I was fine with us going to budget supermarket and she kept insisting it was all fine, she was paying etc etc.
So in the end I gave up and she filled a trolley full of all the expensive fancy things Waitrose has to offer (most of which I didn't like and did not eat!)
She also insisted on buying things for the house and again I declined, I can't afford these things, we get by without them (kitchen equipment, fancy mop and bucket etc) but she had to get them, it was all fine, don't worry.
Then later on I overheard her on the phone to her husband, complaining that I had made her buy all sorts of things I now could not pay for! Housemate of course had kept quiet the whole time letting Mummy buy whatever and why she thought any of it had anything to do with me, I really don't know (I do now suspect he let her think I was his girlfriend...).
Later, the pair of them had a stand up screaming row at the dinner table (when she discovered he'd spent the money she sent him for driving lessons on going to some LARP weekend), ruining a meal I had made, and I had an epiphany. I did not need to tolerate screaming verbal abuse and aggro in my home! I was an adult! I could stop this!
So I threw her out back to the hotel she was staying in and told her never darken my door again! I probably should have thrown him out with her but thats another story entirely!