Commonly used by bogans and Australian Aboriginies to describe something cool or extraordinary. Possibly originated from a lazy pronunciation of "Does alright aye".
People who say dardy that aren't making fun of someone else who says dardy should be avoided if possible and definetaly not befriended.
Rebecca: Hey, Hardy's name is Hardy Douglas!
Clara: You know what would be cool? What if his name was DARDY HOUGLAS??
Rebecca: DARDY!!
Me: Woah, who's Dardy? Are we still talking about Hardy?
Rebecca: Hardy? Who's HARDY?? The only person I was talking about was DARDY!
Hardy: OH MY GOD SHUT UP