Two years ago ds1 (now 6 nearly 7) mentioned that Father Christams couldn't come to our house as we haven't got a chimney!!!!. I tried to come up with theexcuse that mummy stays awake to let him in bla bla bla......
So I went and found a bunch of old keys,(preferably not your own door keys ones that don't fit the front door lock), and a red ribbon and a piece of small square paper and drew a picture of the man himself and got ds to colour it in. On the back I put a note that said "Dear Father Xmas we haven't got a chimney, so here are our special magic keys that only work for you. Merry Christmas !!" Tied the red ribbon to it and hung it on the door Christmas Eve before the kids went to bed. It works a treat every year, ds1 getting a bit suspicious now but it should still work for ds2 who is only 2.5. yrs.
Apparently now you can buy a key like that in the shops these days.