The pharmacist, trying to keep a professional posture, asked what he wanted it for.
He answered, "I want to kill my wife."
"I'm sorry, Sir," the pharmacist replied, "but you will have to understand that under such circumstances I can't sell you any cyanide."
The guy reaches into his wallet and produces a photo of his wife.
The pharmacist takes a look at the photo, blushes and replies, "I’m sorry, Sir. I didn't realize you had a prescription."