The chances of this happening at low speeds are almost non existent. This could only happen if someone is speeding and hits the side with enough force to overcome it. Or maybe if you were in a tractor trailer and high enough to tip over it.

I would play some videogames. I know they're not always that accurate but try jumping over it at 20 or 30 mph in GTA 5. It probably won't be possible. See how hard you have to hit that side to pop it over, and then remember the game is allowing it to happen easier than real life would.