In 1987, two Chicago TV stations had their signals hijacked by an unknown person in a Max Headroom mask-the first station for about 30 seconds and then later that day, another station was taken over for 90 seconds. They used a sheet of moving corrugated steel to simulate the OG Headroom's trippy background, lol.
https://en.wikipedia.org/wiki/Max_Headroom_signal_hijacking?wprov=sfla1
https://en.wikipedia.org/wiki/Max_Headroom_signal_hijacking?wprov=sfla1