A guy is swerving down the road and gets pulled over. The cop says, "You have to take a Breathalyzer test." The guy says, "I can't. I have asthma, and it'll start me on a coughing fit."
The cop says, "Then I have to give you a blood test." The guy says, "You can't. I'm a hemophiliac, and if you prick me, I'll bleed all over the place."
The cops says, "Then you have to get out of the car and walk a straight line." The guy says, "I can't." The cop says, "Why not?"
The guy says, "Because I'm drunk you idiot... didn't you see the way I was driving!"