There used to be a commercial that talked about how "peanut buttery" one particular brand of peanut butter was. As the commercial went on, a bunch of peanuts were poured into a jar, the jar was shaken several times, and when the jar was opened, the peanuts had turned into creamy delicious peanut butter.
Gosh, I spent a lot of time after shaking a jar full of peanuts, but they never turned into peanut butter. I still kind of expect that to work somehow...
A childhood belief about adverts

others believed things like this
- I used to believe that peanut butter was lobster poo.— PaulH(nz)
- My daughter thought that ear wax was peanut butter.— Bobbiemac
- When I was a little boy, I thought that hair was made out of peanut butter.Anon
- i used to believe that the chunks in chunky peanut butter were bugs.— Lauren
- I used to believe that my mother invented peanut butter and jelly sandwiches. Anon
- I thought that barf was what they used to make peanut butter and jelly sandwiches!— Maan o' War