I think what gets us the most about those kinds of lies is that we want to scream, "Do I look STUPID or WHAT??" It's the sheer lameness that gets me. Insulting to our intelligence.
I can't believe he had the nerve to ask the neighbor for "help"--is the neighbor a big drinker who sympathizes?
Yelling and starting a fight are not good options. As for making him sleep on the sofa, what is it you would be "punishing" him for? The drinking or the lying? Either one is a symptom of his alcoholism, and doesn't affect you directly, though it impacts your confidence in his recovery, which might lead you to rethink staying in the relationship.
I think you could calmly tell him that you don't believe his story, that it makes no sense, and leave it at that.