Because it appears my friends do. To cut a long story short we agreed to our friends DD (step DD on one side) staying over with our DD on Saturday night so they could go to a 40th b'day party in Bristol. No problem there. DS#1 then asked if in that their DS (step DS on the other side) could stay Friday night (to do Nintendo and lego-related activities). Again, no problem. But this is where the problem starts. On both occasions nothing was heard from the parents at all as to when they were expecting DCs back or when they would come and fetch. Which meant that we had to ring and ask them whether perhaps they wanted their children back. And they ended up staying most of the day which made things a bit tricky for us.
Now I know I should have been more organised and sorted this before the event but I just assumed that 11am ish would be a reasonable time to go home. Not 3 or 4 in the afternoon. And the second time we rang some jokey comment was made along the lines of 'you can't wait to get rid of them can you?'. Now call me fussy, but surely 'overnight' means just that, not all day.
Must learn to be more specific in my invitations...