In the UK we had a TV advert called 'The green cross code man' who explained the dangers of crossing the road without looking. The punchline of this advert was 'Look out kids, because I won't be there when you cross the road' which I (at the age of 4) heard as 'Look out kids, because I will be there when you cross the road'.
I was quite confused after a week of not seeing this guy until my mom explained what the advert really meant.
A childhood belief about adverts

others believed things like this
- When I was little, I used to believe that deer could only cross the road at the deer crossing signs. — Shellie
- when I saw a sign with a deer on it I always thought deer had to cross the street by it. like a cross walk— only me
- When there was an advert for a "3 peice suite" i thought it was a shop selling 3 P Sweet's!!!— Kate Parker
- I used to think that running cross-country meant you ran across the entire nation!Anon
- I used to believe green houses were made of icicles, because that is what they looked like from the road. Anon
- I used to think that "cross-eyed" meant that people had X's for eyes, like dead people in cartoons.— Tim