A friend of mine filmed my band playing an open mic once when he was absolutely blasted. You can see at one point on the video where he side stepped into a post in front of the stage: The camera pans left... staggaring a little but generally fine, then all of a sudden the cammera is going up down, sideways, then he kinda bounded around the post... and proceded to film my drummer's crotch...

That may well have been one of the nights he ended up getting dragged off the stage still singing "Swing Low Sweet Charriot."

The basic point here is that a little alcohol may help you loosen up, but it won't help you play better. And to be quite frank, you can loosen up without the alcohol and too much alcohol turns you into a faint shell of the player you are sober.