Explain to your friend that it is impossible for him to "trigger" you to drink, and that he is free to drink if he wants to. You can also tell him that even if he could "trigger" you, that it would necessarily mean that seeing a beer commercial or a liquor store would do the same thing. In other words, you would have to hide out in a bunker, and that is not a way to live. If he really is curious, though, I suppose you could explain to him how AVRT works.