prescription

A lady walks into a drug store and tells the pharmacist she needs some 
cyanide. The pharmacist said, "Why in the world do you need cyanide?"

The lady then explained 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! I'll lose 
my license, they'll throw both of us in jail and all kinds of bad  
things will happen! Absolutely not, you can NOT have any cyanide!"

Then the lady reached into her purse and pulled out a picture of her 
husband in bed with the pharmacist's wife

the pharmacist looked at the picture and replied, "Well you never  
told me you had a prescription"