In the U.S. there is this very long-running commercial for a bathroom cleaner with 'scrubbing bubbles.' In the commercial, the bubbles were these little round things with eyes and scrub brushes for moustaches. I always thought that if you poured out this particular brand your tub would fill with these little characters. A friend of mine (who grew up in another part of the country) believed the EXACT same thing, and neither sets of our parents would buy it for us so we could try. They always bought Comet. We're in our 30s now and still marvel at those little bubbles with faces.
A childhood belief about adverts

others believed things like this
- I used to believe that eyes where just like bubbles and if you where to touch them they would pop.— Adam
- Because i could not see them, i thought my farts came out as green bubblesAnon
- I used to think when you farted, bubbles came out.— Nick
- I used to believe that if I swallowed gum I would bubbles when I 'trumped'.Anon
- If i farted in the tub the bubbles would be different shapes.Anon
- I used to belive that, if you swallowed your chewing gum, you'd fart bubbles...— Heidi, Pittsburgh, PA