I am a groomsman and i need YOUR HELP!?

i am a groomsman for my older brothers wedding, i am only 16 and he is almost 25! aside that point, his best friend is going to be the best man and my little brother and I are his next in line groomsmen. I will probably make a speech at his wedding and im wondering what wedding parties are like...my one question is..will i probably end up getting drunk? lol i would also like to know the roles of a groomsmen...thanks