Rudolph the Red-Nosed Reindeer had a nose that, as you know, glowed bright red. On Christmas Eve, the blinking red light on top of a nearby water tower would miraculously become proof positive that Rudolph - and, therefore, Santa Claus - was in the neighborhood.
A childhood belief about father christmas

others believed things like this
- For the longest time I thought that Rudolph the Red-Nosed Reindeer had a very "chinese" nose...Anon
- i used to bielieve if you get hit
in the nose you will turn into
rudolph the rednose reindeer— kurt santana - I used to believe reindeer made it rain because for many years it rained on christmas eve night.Anon
- I didn't know Reindeer existed, I thought they were just christmas animals for storiesAnon
- I was told that for every christmas carol i sang before christmas time santa would give me one less present!— K
- I used to believe that, if God would die, Santa Claus would be boss.— Judith