A lady walked into a drugstore and told the pharmacist she needed some cyanide. The pharmacist said, "Why in the world do you need cyanide?"
The lady then explained that she needed it to poison her husband. The pharmacist's eyes got big and he said, "Lord have mercy, I can't give you cyanide to kill your husband! That's against the law! They'll throw both of us in jail and I'll lose my license."
Then the lady reached into her purse and pulled out a picture of her husband in bed with the pharmacist's wife, and handed it to the pharmacist. The pharmacist looked at the picture and replied, "Well now, you didn't tell me you had a prescription."