I am at a party and their are alcoholic beverages being served. Even though everyone is at the party is under aged everyone is drinking. Should I have one even though I know what the consequences could be?
No, you should not.
One of the most basic Torah obligations is the requirement to look after your personal well-being. Furthermore, the “spiritual consequences” of such behavior can be still worse than the physical ones.
Drinking at parties with underage friends, when aware of the possible consequences, is surely wrongful behavior.
Many halachic authorities (such as the Orchos Chaim, cited by the Beis Yosef, among many others) speak of how it is prohibited to become drunk, and the Rambam (Maimonides) echoes the very negative nature of such behavior. This is all the more true for young, easily influenced individuals.
Good luck and best wishes.