You're right!

The best thing you can do in this situation is remain with your friends in the place you are comfortable. If you go upstairs with the other person, you risk putting yourself in a dangerous situation by being with people you don't know, and who are drinking. You shouldn't accept a drink from another person that you don't know because there is the possibility that they put a drug or alcohol in your drink. Get your own soda and stay where you are comfortable.