How To Fight A Snake?

So, as you know from previous posts, there is a strong drinking culture in Taiwan. Occasionally, I have lunch with teachers, retired teachers, and other members of the community. A retired teacher is very fond of making me 'gambei', or finish my drink (that's why they drink beer out of shot glasses). In my circle of Taiwanese teachers he is known as the snake teacher. He is a small dragon, if you will, as he has influence and likes to assert his power when drinking. Well, I told a Taiwanese friend about my situation and she told me to 'gambei' him first and then 'gambei' him again and, just to make sure, hit him with a third to make sure he knows you're not playing. Well, last time we had lunch I tried it. He eyes were open with amazement when I hit him with the first 'gambei'. The second one he gave me a thumbs up. When I hit him with the third 'gambei' he waved me off. So, how do you fight a snake? You bite the snake first.