I just remembered another thing that had given me the idea of doing a sign for no flashing.
I started driving a Land Cruiser after getting my license. I had some people praying for the people on the road (maybe that’s because of me) and a professor come up to me and say, “You’re driving a Land Cruiser? Cool. Just don’t go really close up behind people and flash them, okay? It freaks me out every time someone does that.”
^ Sparked/drove my idea.