A police officer pulls over this guy who had been weaving in and out of the lanes. He goes up to the guy’s window and says "Sir, I need you to blow into this breathalyser tube for me."
The man says, "Sorry officer I can’t do that. I am an asthmatic. If I do that I’ll have a really bad asthma attack."
"Okay, fine. I need you to accompany me to the station to give a blood sample."
"I can’t do that either. I am a hemophiliac. If I do that, I’ll bleed to death."
"Well, then we’ll take a urine sample."
"I’m sorry officer I can’t do that either. I am also a diabetic. If I do that I’ll get really low blood sugar."
"Alright, then I need you to come out here and walk along this white line."
"I’m sorry, officer, but I definitely cannot do that."
"Why not?"
"Because I’m drunk.