You'll cop a bloody hiding when your father gets home!
In strine, when you cop something, you get it. And it ain't fun.
For example, you can cop a hiding, or you can cop a beating, or you can simply cop it.
It may well be that this is standard English, but Canadians have had difficultly in understanding so we include this definition for their sake.
Learn Aussie English and have laugh on youtube for free: http://www.youtube.com/watch?v=bm36jaYv3zo