We have all heard of at least one incident relating to TV and radio broadcasts being hijacked and used to troll and/or give out false information to the public. Some of these incidents that will be mentioned are just intended to be funny. While others are intended to cause the public to panic.
3: Southern Television.
On November 26, 1977, a TV station in rural southern England was hijacked. Once it was hijacked, an audio message played claiming that the hijackers were from outer-space and conveyed by an individual named "Vrillon of the Ashtar Galactic Command". The hijacking lasted for over six minutes and talked about the destiny of the human race and a disaster to affect "The world and other worlds around you.".
2: Playboy Channel Religious Message.
On September 6, 1987, a broadcast of pornography was disrupted by a text-only religious message. The message read "Thus sayeth the Lord thy God: Remember the Sabbath and keep it holy. Repent, the kingdom of Heaven is at hand"[5][6] (from the Bible verses Exodus 20:8 and Matthew 4:17).". The person responsible was Thomas Haynie, an employee of the Christian Brodcasting Network. He was convicted of Satellite piracy for the incident.
1: "The Max Head-Room incident".
On November 22, 1987, an unidentified man wearing a Max Headroom mask hijacked WGN-TV, a TV broadcasting station in Chicago Illinois. The hijack occurred at around 9:00 P.M. and lasted around 25 seconds. The man could be heard making garbled remarks before dropping his pants, partially exposing his butt. he was then spanked by a woman wearing a french-maid costume with a flyswatter before the screen went black. The culprits behind the Max Head-Room incident are still unknown.
Sources:
https://en.wikipedia.org/wiki/Broadcast_signal_intrusion