A woman enters a pharmacy and asks for arsenic... - What do you intend to do with it? asks the pharmacist, suspicious - It's to kill my husband... - What? You are kidding! I can't sell you arsenic! Very calmly the woman then opens her handbag, and takes out a photo of her husband sleeping with the pharmacist's wife...
- Ah, of course, said the pharmacist, if you have a prescription, it's different...