An article from the bbc here describes an angry parent invoicing another parent for their child not attending a birthday party.
I am not sure if it was a joke or not but, really??? Is this what it has come to? Money before friends?
The fact the BBC posted something like this is another thing entirely, worthy of being in the 'Daily Mail' or 'The Sun'.
The poor bday child will now not have many people turning up to any future Birthdays and be made fun of now. Parent's clearly taking 'The principle' too far.
People not turning up to Birthday parties is common. Sure it's common courtesy to let the other person know, but in real life it doesn't always happen. Remember stuff happens and it may not be possible all the time.