Interjection used on Citizens Band radio as a way to call or attract listeners, either anyone who wil respond or a particular CB user. The CBer says "Breaker" and then releases his microphone, listening to see if anyone answers. Often repeated, i.e., "Breaker breaker."
"Breaker, breaker, this is the Big Duck, is anyone out there tonight?"
"Breaker Speed Queen, you got the Big Duck here."