Australian Slang
An insult. While being called a bastard or a dickhead may not always be derogatory in Australia, there are a couple of species of bird that lend their names to insults. Drongo is one of these, as is galah.

Dron"go (?), n.; pl. Drongos (). Zool.

A passerine bird of the family Dicruridae. They are usually black with a deeply forked tail. They are natives of Asia, Africa, and Australia; -- called also drongo shrikes.

 

© Webster 1913.