The writing profession has a history of being associated with drinking.
A number of authors, including Ernest Hemingway, David Foster Wallace, Edgar Allan Poe, and Truman Capote were infamous for being heavy drinkers, and Hemingway even recommended it as a writing technique.
The following infographic explains how alcohol supposedly enhances creativity, and it gives tips on just how much to alcohol to imbibe to get the creative juices flowing without going overboard, as well as why coffee is the best drink for editing.
I don't drink myself so I can't comment on the effectiveness, but I think the best way to write drunk would be to combine the idea with a standing desk. That way, if you're too drunk to stand then you know you're also too drunk to write.