Although parents may get a little desperate to dream up fresh mischief for Elf on the Shelf to find itself in, there's a line.
For most, shaving the word 'elf' into the back of your son's head would cross that line - but for one mum it was all part of a genius plan.
Mum-of-three Amanda Johns from Swansea has used Elf on the Shelf to keep her youngest daughter Tegan entertained and well behaved for three years.
The Christmas tradition which has surged in popularity in recent years sees a cheeky elf keep an eye on children in the build up to the big day, flying back to the North Pole every evening to report to Santa.
Each morning when it returns it hides in a different spot in the house and is often caught getting up to no good.
Wanting to take the game to the next level, Amanda asked her 16-year-old son Iestyn to skip his weekly trip to the barbers to be a part of the prank.
Amanda then carefully shaved the letters 'ELF' into the back of his hair as he faked being asleep before wiping her finger prints off the clippers and putting them in the mitts of the elf for Tegan to discover in the morning.
It left the seven-year-old shocked, and it's not the first time good sport Iestyn has joined in to keep his little sister excited in the countdown to Christmas.
Amanda, 39, once gave the 'best big brother' a full make-over including lipstick, fake eyelashes, a beauty spot, hair bands and drawn-on abs before leaving the blame at the door of the elf.
The business owner said: "I posted the photograph of Iestyn's new hairdo on Facebook and everyone was shocked.
"They thought I had actually shaved his hair in his sleep, but I am not that cruel.
"He is the best big brother and will do anything to make his little sister smile - she looks forward to the Elf's antics every morning.
"She runs into my room and asks 'where is the elf?!' but when she found him in Iestyn's room with the clippers she was flabbergasted.
"She tried to wake him up, but he is a typical teenager and loves his sleep - I think he would be more annoyed about being woke up than the hair shave.
"I am always thinking of new ideas and I planned this one a week in advance - I asked him not to get his hair cut and he asked 'what are you going to do now?'
"It is completely worth it to see Tegan's face light up in the morning.
"I am always thinking of new ideas and it is a brilliant lead up to Santa's arrival.
"I have previously replaced every photo in the house with a photo of Elf and given Ilestyn a makeover.
"When Tegan had a cold, I put a skeleton on the sofa, and she believed he caught the 'elf flu' and needed lots of chocolate to make him better.
"It is great fun for all of us."
