A dog that sits on the back (the tray) of a utility vehicle, and barks loudly at cars, children and other tray dogs.
Such dogs are usually associated with the so called Australian Bogan
and tradesman (tradie
These dogs are usually aggresive individuals of the blue heeler, kelpie or bull terrior variety.
The tray dog's back arched, owner nowhere to be seen and it's chain teather the only thing holding it back from mauling the weary shopkeeper.