This is one of the best events in Germany in the year.  It takes place annually and there is a true party atmosphere all over the town.  Each day's events are different, although drinking and dressing up in crazy clothes is a common theme of each day.  You do not need to dress up if you do not want to, but it is probably more fun.

 

The parade takes place on the Monday and is entertaining to watch.

 

All the bars and restaurants are very busy and people are exceptionally friendly everywhere.  The main downside is that with so much drinking and no extra toilet facilities, there can be quite a wait when you want to go!  Probably worse if you are a girl though :)