This elf on the shelf craze seems to be very new. Did you do another version of this when you were a child?
When I was a child my mom always would say "Alfie and Andy are listenimg from the pipes". They were elfs that apparently lived in the water pipes or heating ducks of my house and would report back to Santa. Just like with Santa, they were magical and we would never see them. I always thought it was fun and cute amd now they live in the pipes at my house. From what I have been told, a radio dj told on the air one day that he did it for his kids and i guess my granny thought it was funny so she started.