Two Aborigines were driving their old Ford Falcon in the outback one day, when off in the distance they saw a police booze bus. One of them thinks "this is great" and heads straight for it. As they pulled up, the driver winds his window down and says "Two cans of XXXX thanks mate!" The copper looks at him and says "You must be drunk! Get out of the car and blow into this tube for me." The driver got out of the car and said "Sorry boss, I can't blow in that. I got a letter from the doc saying I'm asthmatic and I'll pass out if I blow in that." The cop looks at him and with a bemused look and says "OK In these cases we require you to give a blood sample." "Nah nah sorry boss. Can't be doin' that. I got a letter from the Red Cross saying I'm a Haemophiliac and I could bleed to death. Sorry boss, can't do that," said the driver. By now the copper is getting fairly irate and finally demands a urine sample for testing. The driver looks at him and says "Sorry boss, can't do that either." The copper says "Surely you can't have a letter for that!!!" "Bloody oath mate." says the driver, "It's from Kevins government. Says that you whites can't take the piss out of us blackfellas no more."