I used to think that the slippery road sign was a ski hat - the tires and wavy tracks were ear flaps with the strings hanging down. I thought it meant to be careful driving when it was cold out.
My childhood home was near a cliffside. Along the road, there was a sign that read "falling rock" to warn motorists that loose rocks and sediment could roll onto the roadway. When I asked my father about the sign, he hold me that long ago, a Native American lost his son named "Falling Rock." He wandered away and no one had seen him since. The sign was to alert motorists to look for "Falling Rock." I spent so much time trying to find that damn kid. I was always looking for some kid in a loin cloth.
Before I could really read, a "Fire House" sign was misinterpreted as "Free House". I never thought about it again until Middle school, and realized it wasn't for poor people to live in.
Divided Highway signs used to look like the front half of a men's dress shoe-print. I thought that it was a cautionary sign for pedestrians who might have been walking along the median that they would have to step down into traffic (the arrows).
When I was a child we lived on a short rural street that didn't connect with any other streets.There was a sign that said ,"not a through street". I thought that meant that they were not finished constructing the street and eventually it would connect with another street.I kept waiting for them to finish the street so it would be "through ".
I thought that the "No Passing" sign on a road meant you weren't allow to drive past the sign, and I thought everyone was breaking the law.
For the longest time I thought the "Exit Only" mention on the exit ramp sign on the highway meant you couldn't get back onto the highway from that exit.......the longest time.
Whenever I was younger I thought that the sign "Dead End" literally meant you would die if you went to the end of the road. I was terrified because I lived on a dead end street.
As a child and early teenager I always thought the One Way traffic signs were suggestions, like, "here is one way you can go," instead of, "this is the only way traffic is flowing."
When I saw speed camera signs on the roads I always thought we had entered a zone where we could take pictures!
I am from an area that doesn't get snow but does get lots of seasonal frost and ice. All the bridges have signs posted that say "bridge may ice in cold weather." Until I was fifteen, I used to wonder why every bridge in town was called "may ice," but only when it was cold.
I used to believe that the road signs with an arrow pointing UP (as in up ahead) were actually pointing up to the sky. I wondered for many years how people were able to drive up into the sky!
I used to think that the "lane merge ahead" sign was someone trying to paint the number 11 who just could NOT get it right. I also thought we took this Route 11 everywhere we went.
When I was younger I used to believe that if I went on a boat and it sank only the cars would sink and we'd be happily sitting on the top deck when the bottom of the ship would be on the ocean floor.
They were building a new road and round-a-bout near our house when I was little. I asked my dad when they were going to put the horses on. Having not had a car so not much experience with round-a-bouts my 4 year old self was convinced they were randomly place fairground carousels.
On the interstate some exits say "Exit Only." I used to believe that meant there was no entrance ramp back on to the interstate. If one wanted to return to the interstate s/he would have to go to the next entrance/exit. In other words, it was only an exit.
I used to believe that the UK road signs saying 'Heavy Plant Crossing' meant that my Gran's Banana Plant had gone for a walk from her house and was crossing the road ahead. I never saw it...
I used to wonder why it was okay for my parents to pass the "do not pass" sign while they were driving. I always thought we were going to get in trouble.
Traveling with my parents, we became lost. My Dad was looking for a fork in the road, where he would turn. He couldn't find it. Though I thought it odd, I kept looking out my window for a fork (stainless steel) planted in the middle of the asphalt road.
In the town where I lived there were freeway exits named after states "Pennsylvania" "Virginia". I used to believe that when you got to that exit you were in that state.