Monopoly chiefs have set up a Christmas hotline to prevent board game bust-ups over the festive period.
The helpline is to open in light of a survey that found 51% of Monopoly games end in a row.
The most common cause of quarrels was due to people "making up the rules as they go along".
Smug players who gloat at their good fortune were second on the list of reasons Monopoly games ended badly, according to a survey of 2,000 adults.
Someone deliberately buying property they know you want, even if they don't need it, was also a cause of tension.
The hotline will open from 24th - 26th December, when families will be able to get mediation on any game-based arguments.
Craig Wilkins, Marketing Director of Hasbro UK & Ireland said: "We'll have experts on hand with the official rulebooks to instantly settle any disputes, and advice on how to resolve common complaints, with each person also having the opportunity to make a donation to Childline when they call."
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The poll discovered some Monopoly-based bust-ups have had far-reaching consequences.
One parent recalled leading a game against their 14-year-old son, who became so enraged he threw the board across the room, scattering the pieces everywhere, before slamming the door and going to bed - at 7pm.
The survey also revealed the extent of cheating in Monopoly.
The most common way people buck the rules is to stay silent when they have landed on an opponent's property.
And 13 per cent admit to regularly lifting money from the bank when the rest of the family aren't looking.
This Christmas, families will play an average of four board games, and are most likely to get out a game of Monopoly between 4-6pm on Christmas Day.
The Monopoly Hotline is braced to receive a flood of calls from 6pm on Christmas day as this is the most common time for families to have an argument.
The helpline is free to call from a landline or mobile, but check with your service provider for more details.
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The Monopoly Hotline can be reached on 0800 689 4903