A five-year-old was billed for failing to attend a friend's birthday party - resulting in threats of legal action.
Alex Nash, from Cornwall, was invited to the party just before Christmas.
An invoice for £15.95 was sent by his schoolfriend's mother Julie Lawrence, who said Alex's non-attendance left her out of pocket and his parents had her details to tell her he was not going.
Alex's father Derek said he had been told he would be taken to the small claims court for refusing to pay.
Alex's parents, from Torpoint, had accepted an invitation to the party at a dry ski slope in Plymouth, Devon, just before Christmas.
However, they realised their son was double-booked and due to spend time with his grandparents, which he did.
Analysis: Clive Coleman, BBC legal correspondent
It is all but impossible that Ms Lawrence will be able to recover the £15.95 party "no show fee".
Any claim would be on the basis that a contract had been created, which included a term that a "no show" fee would be charged.
However, for there to be a contract, there needs to be an intention to create legal relations. A child's party invitation would not create legal relations with either the child "guest" or its parents.
If it is being argued that the contract is with the child, it is inconceivable that a five-year-old would be seen by a court as capable of creating legal relations and entering into a contract with a "no show" charge.
It's amusing to imagine what a children's party invitation seeking to create a contract might say: "I, the 'first party', hereinafter referred to as the 'birthday boy', cordially invite you the 'second party', hereinafter referred to as 'my best friend', to the party of 'the first party'.
His parents said they had no contact information for Ms Lawrence at that time.
They found the invoice in a brown envelope in his schoolbag last week.
Mr Nash said: "It was a proper invoice with full official details and even her bank details on it.
"I can understand that she's upset about losing money. The money isn't the issue, it's the way she went about trying to get the money from me.
"She didn't treat me like a human being, she treated me like a child and that I should do what she says."
In a short statement, Ms Lawrence said: "All details were on the party invite. They had every detail needed to contact me."
Mr Nash said he had been told he was being taken to the small claims court because he was refusing to pay.
The party was held at the Plymouth Ski and Snowboard Centre.
In a statement, the centre said: "We would like all our customers to know that this invoice has nothing to do with Plymouth Ski and Snowboard Centre.
"No invoices are ever sent out from the centre to private individuals. This is a disagreement between the two parents involved and the fact that the centre has been named on the invoice is fraudulent.
"When booking a party there is a small deposit to pay on booking, confirmation of numbers and final balance are due 48 hours before the party.
"On the extremely rare occasion that people don't attend parents are generally offered other activities in compensation."
The unwritten rules of children's parties?
- Birthday boy/girl must be given preference for starting activity. Small guests pushing past should be restrained by attending adults
- Party bags or gifts for each attending child - the children will always remember "that party" when they didn't get one
- If you don't RSVP don't think you can just turn up. And if you do, don't expect a party bag (see above)
- Avoid party talk around the parents of the uninvited
- Host child MUST win at least one round of pass the parcel. Sweets within each layer for everyone else
- Children must be given 15 minutes at the buffet before adults are allowed to hoover up the cocktail sausages
Have you ever committed a kids party faux pas? Email England@bbc.co.uk with your tale of breaking the rules