I guess I'm what you'd call a party bug (it's like a party animal, but smaller). I'm not exactly painting the town every night, because I'm uncomfortable in crowds and use phrases like "painting the town" because I'm secretly 80, but I've been to my fair share of social events and town-painting hoedowns.
For a while I avoided big parties, because I'm a socially awkward person and because (and I know this is rare) I didn't actually start drinking until I turned 21, because I was a good little boy. When I did turn 21 and was thus societologically obligated to enter the party scene as its newest and hippest gadabout, I turned to movies to learn everything I needed to know about parties. I don't recommend this plan because, as with most things, movies lied about the big party.
#4. Parties Matter
You didn't hear about Scott's party? Oh my God, you have to go, everyone's going to be there, even and especially Scott. It's the freaking social event of the freaking year, you can't just stay home. Last year someone drank a lot and then did a wacky or embarrassing thing and everyone who wasn't there to see it is an asshole and has been effectively ostracized from society. Come to Scott's party, and also bring ice.
Movies need parties to be cathartic or life-changing. Superbad treats getting to a crappy house party like an epic quest during which our protagonists confront each other with huge secrets they'd been hiding all year. House Party has that big house party. All of the characters in Can't Hardly Wait use the party as the perfect time to make public declarations of love or wild, out-of-character life decisions. The party in American Pie is the holy grail for our protagonists, all of whom have vowed to lose their virginity at that party, because the best part of having sex is thinking "Hey, my buddy is doing this too, cool."
"I hope Steve's having as much fun as I am. I bet he's smiling. What a cool guy."
But that's just movie law. Hollywood can't make a movie about a realistic party where a bunch of people laugh and drink until the police show up at midnight because the neighbors complained about the music, because no one would care about that movie. So instead they make Project X, a teen party movie where someone drives a Mercedes into a pool, someone brings a flamethrower, and the SWAT team is called.
In reality, the amount of fun you will have at a party is inversely proportional to the level of importance you put on that party.
You want to have fun at a party? Get a good group of folks together, throw on some music, and eat a bunch of snacks.
(Although yes, a flamethrower WILL make any party slightly more enjoyable.)
#3. There's a "The Big Party"
You just graduated. You're going away to college in an impossibly short amount of time, and for the purposes of movie magic, you will likely never see the people you grew up with ever again, because in movies, Thanksgiving doesn't exist and the months between June and September have been cancelled.
Or maybe you're in college and finals are over, which means one thing: It's time for that massive and important party that that massive and important frat throws every year (I hear last year they trained a dog to surf and the dean had sex with the school mascot). You've gone to a few parties in your life, but that was child's play, and there's no time to fuck around anymore: It's time for The Party. EVERYONE will be there; even the people who never enjoyed each other's company in school will set aside their differences and come together over the shared understanding that a keg of crappy beer and whatever pop star currently dominates the radio are meaningful and bigger than whatever petty feuds divide any two people. Someone has either access to a secluded cabin in the woods or parents who left town immediately after graduation, because they've never seen a party movie before or are otherwise just uniquely horrible parents.
"We paid for a time share, we're using a time share. Sorry, you're on your own."
Oh, also remember that this big huge party that everyone's going to is literally the only social event left. So if you want to profess your love to or get in a big fight with someone, this enormous party will be your last opportunity, according to movies. Hell, in Can't Hardly Wait, the protagonist graduates high school, goes to a party with his entire school five hours later, and then leaves town to get ready for college the next day. And that's totally normal.
Remember that you don't actually want to party with your entire high school or college. Why would anyone? I'm not saying my high school was terrible; quite the opposite. Everyone I went to school with got along, or as much as a bunch of hormone-filled idiots can get along. There were 247 kids in my graduating class, and most of them were nice and pleasant to each other, and we threw a senior prom with no fights or wars or anything. But there was a reason cliques formed, and it has nothing to do with popularity or "cool kids vs. freaks"; the people who had similar interests found each other and formed little groups. When I graduated high school, I didn't want to drive out to some cabin full of a bunch of people with whom I'd had nothing in common; I wanted to hang around with the solid, amazing, and weird group of friends I'd gotten close with over the last few years and argue about pop culture and sit on the beach late at night smoking cigars or, if my mom is reading this, quietly watching educational programs on television.
This won't change in college, either. You'll want to go to a few big frat parties full of strangers, sure, because it's important to make new friends and remind yourself why you hate big frat parties (everything is sticky), but mostly you'll find that you'd rather hang out with the people you actually like doing the things you enjoy doing the most (quietly watching educational programs on television).