A song by C.W. McCall (real name William Dale Fries, Jr.) about the CB radio craze of the 1970s, "Convoy" reached #1 on Billboard in 1975. The song contained an imagined conversation between truckers via CB radio, with CB slang. Users had handles (call signs or nicknames), which they used to address other truckers while conversing. "Breaker" was how users informed each other of wanting to start a transmission on a channel. Channel 19 was the mostly commonly used channel, hence the term "Breaker 1-9, this is ..."
The references made in the song (see link above for explanations) may seem foreign to people of today who have grown up on cell phones and text speak. I was only a little girl when the song came out and I have very few, if any, memories of anyone using CB radios. This meme has shown up on the web:
I guess, in a way, that was true. Check out this video to see a CB radio.
The song and the CB/trucking craze inspired a 1978 movie of the same name. Earlier movies, like Duel and Smokey and the Bandit were also inspired by the craze. Trucking and CB radios were then at their peak.
The song must have been a favorite of the producers of The Simpsons, as one episode had Homer singing the song and another had a parody called "Christmas Convoy."