Put a drunk person in a cold shower.
Why Not? The shock of the cold could cause them to become unconscious.

Give a drunk person food, liquid, or any kind of medicine to sober them up.
Why Not? Anything in the mouth of a semiconscious person can cause vomiting, choking, or inability to breathe.

Allow the person to exercise.
Why Not? The likelihood is that the drunk person will injure him- or herself or you.

Laugh at, make fun of, or provoke the person.
Why Not? Alcohol can make a person feel invincible. Egging on a drunk person could cause him or her to do something dangerous that could result in injury to him- or herself or others. And even minor provocation can cause a happy drunk to become an upset or violent one.

Allow the person to drive a car, boat, bicycle, or any other vehicle.
Why Not? You already know why not.