An Australian word, which is derived from a type of bird of that name (or so I'm informed) that lives down here. It was observed by the "Old Australians" as acting rather crazily, and thus an Aussie will call someone a drongo to say that they're an idiot. There are a number of alternative Australian pay-outs of this nature and calibre, such as clown, galah, wakka, minda, and many others.
"Scotty! What ARE ya doing, ya drongo?"