A policeman pulls a driver over for swerving in and out of lanes on the highway. He tells the guy to blow into a breathalyzer.
"I can't do that, officer -- I'm an asthmatic. I could hae an asthma attack if I blow into that tube."
"OK, we'll just get a urine sample down at the station."
"Can't do that either, officer. I'm a diabetic. I could get low blood sugar if I pee in a cup."
"Alright, we could get a blood sample."
"Can't do that either, officer. I'm a hemophiliac. If I give blood, I could die."
"Fine then, just walk this white line."
"Can't do that either, officer."
"Because I'm drunk."