Back in my college days at SDSU we had a "Japan-America Friendship Club" that would organize events like beach side bonfires attended by the ESL students from Japan and gaijin who were trying to learn Japanese. It was at events like these that I learned the ancient art of speaking a foreign language while mildly inebriated, which allows you to communicate significantly better than you otherwise would, at least until you pass out. It's as if there's a barrier in the mind that's always trying to keep you from making a fool of yourself, which gets deactivated when you have a beer or two. Of course, the benefits of alcohol on foreign language ability are as fleeting as cherry blossoms in the spring, and you can quickly find things going in the opposite direction if you're not careful. Happily, the Japanese have another tradition I've been known to make use of from time to time: whatever a person says or does while under the influence is generally forgotten about and ignored forever. Isn't this country great?
Alcohol can help your Japanese-speaking ability...and then harm it.