Tracksuit pants. The lower half of a tracksuit. Often worn in Australia instead of shorts, trousers, jeans, skirts, dresses, slacks, etc, because they are comfortable. Acceptable attire amongst family, friends and neighbours (everybody loves good nieghbours). A derisive term when applied to strangers.
"I don't care how muuch you paid for your jeans, only fat cunts would wear their 'tracky dacks' in public!"
Tracky dacks is the Australian slang for sweatapants. There should be a national tracky dacks day every October 18th. There is such thing as half tracky dacks as well, sport shorts.