Drink their stash before they get to it.
pray to the One who can help.
That's very forgiving of you. You must be a wonderful person.
slip them those antibiotics that make you violently vomit if you so much as have a sip of alcohol?
There's nothing you can do until the individual who is drinking finally decides to deal with the problem.
Didn't matter what people said to me when my drinking was bad, I really didn't care until it put me in a place I never want to be at again. Sometimes hitting rock bottom is the only place people realise they've got a problem and need to sort it.