When I was little, I always thought that the turn signals actually turned the car. Of course, that didn't explain what the steering wheel was for. I came to the conclusion that the steering wheel was manual and the turn sighals were automatic: A driver turning a steering wheel could handle all the little bends and turns in the road just fine, but actually rounding a corner was beyond the strength of mere mortals, and so mechanical aid was needed. If you know absolutely nothing about cars except from what you glean by watching your parents driving, this explanation makes a lot of sense. I was older than I'd like to admit when I found out I was wrong...
A childhood belief about cars

others believed things like this
- Because of cartoons, I thought that to drive you'd just turn the steering wheel back and forth constantly. — Mitsuki
- I used to think that drivers accelerated by turning the steering wheel.Anon
- I once thought that there were little mice under the wheel on Wheel of Fortune making the wheel move— Kara
- I thought that cars could only make turns when you used the turn signals...— Toby
- i used to believe the turning signals on cars helped them turn sharp corners.— Julia
- I used to belive that the turn signals in a car were automatic & they told you where to go!— Lauren