A 'drogan' relates to the terms bogan, derro and drongo. A drogan is of the lowest standards and is someone who is poor, has no fashion sense and is a complete dumbass. You might use it to describe someone who you think should have been shot when they were born.
A person you hate intensely not because they deserve such hatred but because they serve as a focus for your general hatred. A healthy way to dispense with excess animosity.
Jake's not really that big an asshole. He just serves as my hate sink.