A letter once a year to let you know whether I've been good And all the kids at school said you're not real But I knew the truth, nobody, nobody, nobody else Only Santa knows when you're asleep Only Santa knows what cookies you leave Only Santa knows if you really do believe Only Santa knows I saw you cross the moon I ran inside to go straight to bed In the magic of the night I closed my eyes and watched them display Nobody, nobody, nobody else Only Santa knows when you're asleep Only Santa knows what cookies you leave Only Santa knows if you really do believe Only Santa knows I can't wait till Christmas morning before the day's begun I'll check the garden to see if all of the carrots are warm Till mom and dad that we got presents Underneath the tree I'll have to wait and see Cause only Santa knows when you're asleep Only Santa knows what cookies you leave Only Santa knows if you really do believe Only Santa knows Only Santa knows Only Santa knows He's on the roof He's on the roof He's on the roof He's on the roof He's on the roof