If I had a friend like that, I would suggest they lower their alcohol intake. True story: the only time I ever got blackout drunk was also when I burned my hand by tripping and holding on to an iron fire ring for support. (It healed, don't worry.) That was enough to motivate me against ever getting that drunk again. Some people don't seem to take that kind of thing as a hint, which seems sort of insane. It's certainly not healthy.