Reason: Intoxication (Hadith No. 243)

Salam,
Bismillah.

Volume 1, Book 4, Number 243:

Narrated Aisha:

The Prophet said, “All drinks that produce intoxication are Haram (forbidden to drink).

The reason for this is: intoxication. Anything which has this effect is forbidden. Because a Believer has to be alert all the time. He has to observe some rules and etiquette when in public or alone. For example, praying five times a day, respecting women, observing fasts, going to the Masjid etc. The Believer won’t be able to do all these things properly if not in his senses.
This is just one reason I came up with. Allah made intoxicating drinks Haram and He must have other reasons for it too. :)

Say no to alcohol, or intoxicants for the matter.

Wassalam.