cut your head off
An insult used in New Zealand and Austraila. Apparently telling one to cut one's head off is a bigger shot to the balls than calling one a bugger.
American: Might as well cut your head off
Aussi: What did you just say ta me?
*Ameircan has his arse handed to him.*
Aussi: What did you just say ta me?
*Ameircan has his arse handed to him.*