The viral trend originated in the US in 2005 but has since made the trip across the pond.
The Elf on the Shelf story was created by Carol Aebersold and her daughter Chanda Bell – and was based on their own personal Christmas tradition.
The story goes that Father Christmas sends out pixie elf scouts each year to visit little boys and girls across the globe and check if they have been naughty or nice.
Every night in December, when the kids have drifted off to sleep, parents pose the elf which comes with the book in various locations around the house.
The authors are keen to stress that elves can not be “bought”.
Instead they are “adopted” from adoption centres – like Poundland and John Lewis – over the festive period.
And the trend even comes with its own #elfonashelf hashtag.
But some cheeky parents have taken the opportunity to place the elves in hilarious, compromising or crude positions, sharing photos of them online.