junkyard dog

Meaning

Noun

• An aggressive dog which guards a scrapyard or junkyard.
• An animal or person with an especially nasty and combative demeanor.
• A hot dog laden with toppings, such as onions, pineapples, or chili

Origin

• From junkyard and dog. Non-literal sense popularized by the 1973 Jim Croce song "Bad, Bad Leroy Brown" (see citation below).