Games! Get a deck of cards and play some good drinking games.
One game you can play without cards that's fun with a big group of people: Memory. Sit in a circle and go around the circle counting to 15. Whoever "lands" on 15 replaces a number with a word. The object is to replace all the numbers with words, and to keep going around the circle repeating the correct sequence of words/numbers. If a word/number is missed, the person who missed it drinks. If the entire sequence is finished without mistakes, everyone takes a drink. You play until all the words are replaced and you can make it through the whole sequence without a mistake.
The most important thing is to have fun yourself
Don't stress out too much.