When my older brother and I were younger, he subscribed to Nintendo Power. One day, he received an ad that was a little yellow packet with the words "Do Not Open This" in big, "exciting" font.
"Why can't you open it?" I asked.
"If you open it, you'll go blind," he joked.
I was terrified out of that little packet for over three years until I finally got the nerve to brave opening it up.
It was just an ad for a renewal subscription of Nintendo Power.
A childhood belief about adverts

others believed things like this
- I used to think that 'Child Locking' only worked on children and that older people could still open the door.— Anonymous Whistleblower
- my brother told me that if i ride my bike with my mouth open i will swallow my tounge. Anon
- I used to think that you could get arrested for having a packet of Rizla's that had bits torn off the top...— Patch
- I used to believe that the Super intendant was the Super Nintendo.— Lecia
- I used to believe that if you sneezed with your eyes open you would die!— Becky
- I used to believe that you could break open the Television and get the toys— Certeria