This study compared the effects of consuming 25g of protein to 25g of protein plus alcohol after a workout. It was found that consuming alcohol after a workout severely impaired post-workout muscle protein synthesis. If your goal is to gain muscle, avoid alcohol after your workout and consume alcohol in moderation when you do drink. Have fun but take care of your gains!
Source: Parr, E. B., Camera, D. M., Areta, J. L., Burke, L. M., Phillips, S. M., Hawley, J. A., & Coffey, V. G. (2014). Alcohol ingestion impairs maximal post-exercise rates of myofibrillar protein synthesis following a single bout of concurrent training. PLoS One, 9(2), e88384.