So a lady walks into a drug store...
A woman walks into a drug store and asks the druggist for some arsenic.
The druggist asks "Ma'am, what do you want with arsenic?".
"To kill my husband."
"I'm sorry Ma'am, I can't sell you any for that reason."
The woman then hands him a photo of a man and a woman in a compromising position. The man is her husband and the woman is the druggist's wife.
He looks at the photo and says, "My apologies, I didn't realize you had a prescription."
(thank my cousin for that one)