Alex Nash, 5, accepted an invitation to a friend's birthday party in December—and when the UK boy ended up skipping it because he also had plans with his grandparents, his parents got an invoice in the mail. Julie Lawrence, the birthday boy's mom, sent the bill for about $24 to cover the cost of Alex's non-attendance at a ski and snowboard center, the BBC reports. She says Alex's parents had her contact info and could have let her know in advance he wasn't going to be able to make it. But Alex's dad Derek denies that. He adds, in reference to the invoice they found in their son's schoolbag, "It was a proper invoice with full official details and even her bank details on it." (The Plymouth Herald has pictures.) He's refusing to pay, and says Lawrence has threatened to take him to small claims court ... and her son will reportedly no longer play with Alex at school. Four amusing side notes: