How should you act during a role-play with your classmates refusing alcohol?

Simply say that you have drank alcohol in the past and ended up in hospital because you became seriously ill, the doctors ran several tests and you are highly allergic to alcohol, even wine. You could also tell your friends that it could be lethal and it is not uncommon for people to have this allergic reaction and to be very careful using alcohol especially while on any type of medication. I hope that this helps you.