There is also the stereotype that fraternities do nothing but drink, party, and haze. Hazing, although once a common fraternity tradition, is now nothing more than an urban legend. Learning what you are becoming a part of is an important part of pledgeship.
Greek organizations do a lot more than party, too.
Each organization has their own philanthropy, or charity, that it does work with. Ours happens to be the Muscular Dystrophy Association. Every year, we hold a fundraiser to benefit this charity. We also organize beach cleanups, events for children, and other community services. It doesn't matter if you are in another organization, or even if you aren't in one at all.