A lady walks into a pharmacy.
She asks the pharmacist for cyanide.
Pharmacist: “I can’t sell you that. It’s a deadly poison.”
Lady: “I know. I want to kill my husband. He’s having an affair.”
Pharmacist: “I don’t care. I can’t sell you cyanide.”
Lady shows him a picture of her husband and the pharmacist’s wife in bed together.
Pharmacist: “Oh … you have a prescription.”