Years ago we sometimes had an evening meal with another couple, usually about 8pm. We always had a babysitter when we went to them but they arrived for an evening meal here with their child - probably aged about 3 or 4 - in pyjamas in a sleeping bag and said the child would be all right upstairs on one of our beds, she would soon go to sleep and they would take her home asleep in the car and put her to bed when they got home. I was a bit taken aback, there had been no prior warning and TBH sometimes our beds were not made or tidy.
I once asked someone round for lunch, didn't know her all that well, we were on a course together, and she turned up with her dog. It was well-behaved but I wasn't happy about it.