I'm about the same age and like and dislike the same things about alcohol. I never had a top hat, but did have tails and a cane. Yay.
Don't forget this, whatever you do.
1) Try saying you haven't found a drink you like yet and you aren't in the mood to experiment. That implies you're one of them, don't judge them for drinking, is an adequate and lasting refusal, and gives you a chance to redirect conversation if they pry about your "mood". "I'm just thinking about..." works fine. You may have to tell them what you don't like is the taste, but they already know that and are asking anyway, because they're silly, so they won't be as shocked.
Have fun, but never say you don't need alcohol to have fun. Instant Stick in the Mud status from that one.
2) Social conventions vary widely; follow people's lead. Use coasters when appropriate, don't chug anything unless someone tells you to or there's loud music playing, and don't blame the alcohol for anything you do or say that isn't a result of poor coordination.
Following what others have said about drinking less: You're drinking less because you're a lightweight, not because you want to be the least drunk. That way they're the empowered ones, having higher alcohol resistance traits than you. Match their demeanors, but don't fake slurring or stuttering. Not attempting to move is more believable than stumbling. If you're as affected as they are, or act like you're not experienced with alcohol and having any is already significant, you'll be easily dismissed and no one will question your light drinking.
Random tips for specific drinks: If you're doing shots, take them together or alternate, just follow their lead. Bow out if you want to, acting like it would be a bad idea not to. For bottled beers/wine coolers/whatever, you might be able to just have one by drinking it slowly. If it's a situation where someone gets up and asks who needs another, you can have half of what the average person there has without being weird. Wine poured in glasses and refilled from a bottle tends to be topped off periodically, but emptying less before being refilled means you drink less. I find mixed drinks that contain ice/water/soda taste nastier than just whatever liquor goes in them, so I just get a shot of that when I can. No one has minded yet, it's cheaper if you're out somewhere, and you're drinking less.
3) It could just be force of habit, since other people also like physical disorientation and tend to do that when they get together. People aren't usually good at thinking of things to do, and even when they are they throw alcohol in there too because it's fun. You have to learn to drink or blend as a non-drinker because people are boring but you still don't want to miss out on interacting with them.
If they know each other professionally, alcohol designates it as a social situation and not just a professional one, as opposed to a team building party sort of thing. If they aren't happy in their jobs (or upon getting home after losing time and energy to their jobs), drinking signals a mini-vacation so they can prove to themselves they have a life outside of work.
It's been over a year since I graduated from college, but only recently have I felt like I'm officially entering the "adult world." Navigating the social arenas of the adult world requires the same basic skillsets as the college world, but a lot of the rules are different and I'm struggling to learn them. Among them is how to drink socially.
As a general rule, I don't drink. I don't like the taste of alcohol. I don't like paying the exorbinant prices that alcohol costs. I don't like the feeling of my brain slowing down and making it harder to string sentences together. I don't mind the physical disorientation - that part's pretty fun. But that part also seems to be slightly frowned upon in an "adult" setting. I'm not opposed to it for any particular moral reasons.
When I do drink, I prefer to get it over with as fast as possible, whether I'm officially drinking a "shot" or not. In college that at least had a sort of "daring" quality that was respected. But it's pretty obviously taboo at classy cocktail parties and even somewhat taboo at "casual adult" parties.
So there's a few separate questions I have:
1) Are there any good, cached buzzword phrases I can use that'll make it socially acceptable to not drink? "I just don't like it" seems to draw disdainful stares, and while I haven't tried it I get the sense that saying I'm morally opposed to it would make me look even more like a stick in the mud. Saying "it's ridiculously expensive" makes me look like a cheapskate.
2) If I must drink socially, is there a breakdown of the general social conventions I should be aware of so I don't need to have them pointed out to me over the course of the next few years?
3) Is there any particularly interesting analysis of *why* drinking is so important to social interaction? Knowing the underlying causes might at least give me some better appreciation for why I have to learn this other than "because!"