You may have to provide more information to get any really useful suggestions, but based on your request, there isn't much that can be done or said to "shock" or "scare" an alcoholic into getting sober. They generally need to 'hit bottom' and be allowed to face the consequences of their drinking before they will be in a state of mind to consider quitting drinking and accepting the help they may need to do that (like going into a treatment center or getting involved in Alcoholics Anonymous).

In many cases, the best you can do is make sure that nobody is preventing the alcoholic from facing the consequences of their drinking - do not make excuses to their boss to try to help them keep a job, do not lie for them to help them avoid legal consequences, do not bail them out of jail when they get arrested because of their drinking, do not give them money, etc.. 

There is a program separate from AA that provides very useful support for the family and friend of the alcoholic. These are people who know what you are going through and who can help you learn the difference between encouraging the alcoholic to get well, and accidentally helping the alcoholic to stay sick. This program is called Alanon. I encourage you to check it out.

Might want to read with him the definition of alcoholism from the AMA especially the part that it is progressive and if not arrested by total abstinence ends in death. That still might not do it.  This disease is mostly...cunning, powerful and baffling.  Little did we know.   Keep coming back and check out the Al-Anon board also.