According to this story, people in Turkey are dressing up as doctors and doing door-to-door hypertension screenings. They discover high blood pressure, give the people pills to treat the high blood pressure, but they are powerful sedatives and the criminals ransack the house while their victims are passed out. The police replicated the experiment with placebos, and 86% of the people took the pills.
The moral of the story is, don’t take candy from strangers, and don’t take drugs from doctors going door to door. Do you really need to be told this?