I don't even know if it is an actual logic puzzle, or just something that happened.
My dad used to like to ask these kinds of riddles. Anyway, he worked for the California Department of Highways many years ago and I remember him telling my mom about a semi-tractor trailer that was driving down the freeway and when he came to an overpass, well, you can guess. He was too high to drive under it. So somehow he managed to stop in time before being thrown through the windshield, but he got stuck. He couldn't move the 18-wheeler forward or backward. All the engineers and police and bystanders were trying to figure out how to get this huge semi out from under the overpass.
Finally, after many hours of figuring and adding and subtracting and discussing the possibility of tearing out the overpass, a little boy approached them and gave them the solution to their problem. (This is really an easy one.) (And no doubt really old.)