Ahh, great Craic! I remember a day in the catskills at an all-day Irish music festival. The sound system went out during someone's set and a big burly technician came out to have a look. As he bent over the monitor, his butt to the audience, his jeans rode halfway down his ass. A guy I know, thinking on his feet, yelled out:

GREAT CRAIC!

Not a dry seat in the house...

as for the didg, it just sounds so much like an Autsralian word(Kangaroo, Jackaroo, wallaroo, boomerang, billabong, etc) that it would be an awful coincidence for it not to be Australian, don't you think? Not that that makes it impossible, but it certainly warrants skepticism...