It really depends on the organization itself. Some fraternities are very similar to those pictured in Animal House and the like, and some couldn't be more different. As an example, compare the "average" NPHC fraternity (e.g. Sigmas, Alphas, or another traditionally African-American organization) to the "average" IFC fraternity, and you'll notice a world of difference. There are also all sorts of differences within the IFC/NPHC fraternities themselves. Some are racist pricks, others are constant drunks, and others still are regular, easy-going guys.
To say that all "frat boys" (which, as someone mentioned, is generally seen as a derogatory term by the greek community) are the same is to say that all black people are the same, or all white people are the same. Greeks are just as diverse as any other group of people.
And no, for the last time, it is NOT "buying friends." That is the most ignorant and regurgitated stereotype of all time. The minute somoene makes that argument, I know they have pretty much no idea about the Greek system as a whole. I'd be surprised if my dues topped $1200 total for the three years that I was an active member of my fraternity at Georgia, and I could break down where every dollar of that money went. The reason that most "typical" fraternities charge more in dues is because those dues also include rent and food at the fraternity house, which actually works out to be a pretty good bargain.