I didn't include a lot of biographical detail in my biography (whoops!), so here's something you should know: at MIT, I am a proud member of the Theta Xi fraternity. Last Friday, with Rush winding down, we finally gave out bids to some awesome freshmen (and a sophomore!). They'll have until 8:00am this Saturday to decide whether or not they want to pledge.
Rushing isn't an easy job, and popular culture doesn't make it any easier. Many MIT freshmen, myself included, come to MIT with all sorts of misconceptions about fraternities. We're all boorish jocks or insufferable rich snobs, or maybe both. We're actively antagonistic towards women. We wear pink polos with popped collars. These kinds of misconceptions probably prevented some freshmen from going through Rush at all, at least for more than a few flashy events. Those who did give Rush a fair try may have been surprised to learn that MIT fraternity men are both diverse and intellectual, respect women (at least in my experience), and don't wear pink polos with popped collars any more than non-fraternity men. There are legitimate reasons not to pledge a fraternity (for example, because you have too many extracurriculars on your plate), but tired stereotypes shouldn't be one of them.
Now, if you've gone through Rush enough to get a bid, you probably already know this. Even so, you might have a parent or girlfriend (or boyfriend!) who doesn't, who is skeptical about fraternities, and whose opinion matters to you. To them, I say: please don't let the availability heuristic get to you. MIT fraternities are very different from fraternities in general, and are also very different from what you've heard about fraternities. I would never have joined one if it had been any other way.
If you or someone close to you have any questions about pledging, ask someone about them. The brothers of any fraternity who gave you a bid want you to make a well-informed decision as much as you do. They're not trying to trick you: it doesn't help anyone if you pledge a fraternity that's not right for you. You can trust them. If you want another perspective, though, you can also ask rush girls for advice. Parents of brothers are also sometimes available to talk to.
The worst thing you can do is not ask at all and just have a vague worry hanging over your head that could be dispelled by a short conversation. ("Oh, so you don't actually make us walk over Doritos?") This is MIT, after all. Get curious. Collect information. Then make your decision. Good luck!