Did you ever hear about the satellite TV takeover on HBO back in the 80's?
One day after the (obviously completely unrelated) Chernobyl disaster, John MacDougall was angry with HBO for having ridiculous prices, which was hurting his satellite TV business.
He used his equipment, which he had earlier been using for a legit business-related purpose, to take over the signal and put the following on the screen about a half hour after midnight (hence the name, I guess) for about five minutes:
GOODEVENING HBO FROM CAPTAIN MIDNIGHT $12.95/MONTH ? NO WAY ! [SHOWTIME/MOVIE CHANNEL BEWARE!]
he did this during a showing of "The Falcon and Snowman", some historically based spy movie, and p***ed a bunch of viewers off.
HBO actually had to give up trying to override his pirate signal because he used so much transmitter power. HBO didn't want to risk burning up their own equipment so they let it ride for the 5 minutes.