What your roomate and the Admin said is pretty accurate. For me anyway. :)

I'm sort of crushing on this guy right now, as are two of my friends, so I have a pretty good idea of what happens for three different people. (completely different people)

I do get warm, fuzzy, happy feelings when he looks at me. And talks to me. And I'm normally a bit too shy to look into his eyes when he does. But I normally don't talk to him, I talk to his friends, who are a lot more... talk-able-to.

One of my friends on the other hand, has a crush on this boy who probably doesn't even know she exists. Well, we've talked to him before, but he probably doesn't know her name or anything. If my friend, let's call her Riri, bumps into The Boy she gets all excited. She's too shy to talk to him though and, anyways, we normally don't just walk up to random people and start talking to them. But this boy, Lars, is friend with The Boy, and Lars likes to bother Riri, so we use that as an excuse to talk to The Boy. It has worked about three times out of five. Riri didn't talk to The Boy that much though.

Now my other friend, Cissy, has a crush on Another Boy. Another Boy hates her though, or at least thinks she's ugly or something, because he's just that shallow. -_- But before Another Boy hated her, he just didn't know she existed. Cissy knows where his locker is, his locker combination, what class he's in, and gets really, really, REALLY excited if he just bumps into her (we have really small hallways) or looks at her.

Hope this helps! :) 

I had a crush before. It involves much staring at a person when their back is turned, and making excuses to your parents as to why you want to go to stuff that they are also going to, and pretending that it's for some other reason. Also if you tell someone that you like them, it will be your best friend, and you will swear them to secrecy. If you are around them at a party, or something, a friend and you might have a conversation like this: "What are you staring at?" "Um..." And if they look at you then you look away. Fast.

It gets even weirder when the other person also has a crush on you.

Oh, I forgot to add, you could also read some fanfiction. Anything Twilight, Snape/LilyE, Draco/Hermione, normally works. :)

Prepare for an extreme overload of awkward and probably unnecessary information. The first bit is what a trusted source said (or rather, typed) when I asked her; the second bit is my own opinion. 

"Crushes are a strange mixture of soaring elation, and obsessive worrying. When the crush is around, you feel very awkward, but once out of the crush's presence, you can spend hours reliving the encounter in your mind, cringing over any perceived fault of yours or indifference on the part of the crush, but touching on any perceived attraction to you on the part of the crush.  As when you lose a tooth, you keep going back to the high and low points.  You take the high points, and think about how you could have made them develop into more, giving yourself over to fantasies of the crush touching you on the arm, and asking you to go for a walk or a meal or a movie, and then having this experience culminate in a kiss that makes you thrill and tingle.  Your thoughts then turn into warm, rosy, billowy, indistinct joy.  Of course, the opposite happens too.  If you see the crush talking to someone else, or you hear someone else talking about how she likes the crush, or you do something really awkward in the crush's presence, you start to worry.  You compare yourself to other possible object's of the crush's affection.  You think the crush could NEVER like someone as (stupid, ugly, pimply, etc - take your pick) as you.  Eventually, the crush finds someone else, and you think you'll never find love, or the crush does something stupid and you can only think, "Ewww!  What was I thinking?!?." or you find another crush, or, best of all, that kiss finally happens."

My recounting of the experience is a bit less... well, technical, but it might be kind of useful. I've been friends with A Boy since fourth grade, and I've liked him because he's smart, funny, creative, nice, and a good writer. :) We used to just be friends, but over time I developed a crush on him, which entailed (in the early stages) acute awareness of The Boy, such as where he was and what he was doing, feeling inexplicably happy when he talked to me, and wanting to spend more time with him but feeling really uncomfortable about asking. Since then, it's been a little different. Whenever I talk to him, I feel sort of... well, not just nervous, but also kind of pressured, as if everything will be ruined if I slip up. I feel absolutely elated when he compliments me on something, even if it's just, "Nice yearbook story, Alex." I fantasize about The Boy asking me to go to the school dance. It's really a unique experience, and it's kind of a mix of awful and exhilarating.
About warm fuzzies and butterflies: I find that these are two completely different things. Warm fuzzies mostly occur when the crusher is looking at the crushee, and they feel sort of like you're holding a hot water bottle to your chest, accompanied by a general happy feeling. Butterflies seem to occur more when the crusher and the crushee are actually having a conversation, and are of just a slightly different species than the kind you get when you're going to perform onstage, or when you're waiting in line for a scary but fun roller coaster. The two are not mutually exclusive, and are often found happening at the same time.

I told you it would be an extreme overload of awkward and unneccesary information!