I used to believe that Gustavo Dudamel's (principal conductor of LA philharmonic) name was La Phil because all the advertisements for LA philharmonic said "La Phil", with a picture a Gustavo Dudemal conducting. Fortunately, I only believed this for about 4 years until my brother told me that the conductors name was Gustavo Dudamel, not La Phil.
A childhood belief about adverts

others believed things like this
- Phil Collins song "I missed again" - I thought it was "I pis*ed again" - didn't realise he was an alcoholic?!Anon
- I used to think that a conductor while conducting told the players what to play as opposed to their music.— Daryl
- When i was small boy i think that there will be a conductor in the aeroplane,like in a bus.— Umesh
- My friend believed that when lightening flashed, you better smile because God was taking your picture! — Linda from Southern California
- My older brother once told me that Aussie shampoo was made from kangaroo pee. I avoided using it for years!— Annie
- My older brother told me that everytime you sneezed your lungs would bleed. I believed this until I was 21!— Gem