Well I got to blue belt in Judo. That's enough to take out a drunk if you absolutly have to. Then again running downhill will take care of him as well if he tries to follow. It worked once for me.
Its not enough to attempt to save one's a$$ in other situations. The only much larger guy I ever put down had the brains of gnat when he punched me in the back of the head while standing two steps below me while we waited to get into a bar. (he took exception to the fact that I would not allow him to cut in front of me. which I was supposed to do because he was 6 inches tallerthan me). I turned, got punched in the face, punched him in the face , downwards obviously, then knee'd his chin. If it hadn't been for the crowd behind him he'd have had a really bad fall. As it was the crowd took exception to him and pushed, shoved him out the door.
the bouncer then decided I should not be allowed inside at all so I had to leave although he did escort me out and the big guy was gone by then
Oh well, some liver cells lived another day.