How can I tell my boss I don't want him to make me drunk anymore without pissing him off?

I had not drunk any alcohol in about 12 years. At least not enough to feel its affect. I would maybe have a shandy with my father on his birthday, but thats about it.

But my boss keeps lots of bottles of 21yo whiskey behind the bar for the staff, and enjoys making people drink it.

It costs lots of money for just one bottle, 100’s in fact, and my boss is a very friendly person. I know he likes to give it to me as a reward and sign of friendship, but I’m not cut out for drinking.

How can I stop him giving me booze each night.

The last two nights I have been drunk… the first time of my own doing yes, but I still don’t like it.

If I don’t have a whiskey, he wont have one either, he does not drink alone, he works 17 hours a day, yes, 17, and I feel like I am denying him his very well earned reward if I turn him down.