Jaggoffs

Honestly, before this past weekend, I thought that 'jaggoff' could possibly just be a word that Tracy made up and yells at the sideline before we play clam, but I was proven wrong!
Nick decided to call a store in Sq. Hill to see if they were still open in the evening, here is their conversation:
Man: "Uh, hello?"
Nick: "Hi, is this The Exchange on Forbes Ave.?"
Man: "Yeah, we're really busy, so leave me alone you jaggoff" click....

Is that bad customer service?