We've all been there before. You're at a party with some friends, and everyone's having a good time. It's all great and fun, until someone gets a little bit too into their good time, so to speak. We've probably all been on both sides of this, maybe one night you're the one feeling yourself, and the next you're the designated babysitter. There's only one side that you can really be in control of, and that's when you're in the not-so-favorable position of baby sitter.
It can be a pain, that's for sure, but once you've assumed the role, you've got a job to do. Your friend is in a baaad spot, and needs your help if and when things get any worse. The first thing you're going to want to do, is keep a close watch on them. You don't want to hover over them just yet, because they might not be entirely trashed, and you don't want to make a spectacle of your friend. Trust me, they'll take care of embarrassing themselves just fine, they don't need your help in that department.
If you've been keeping a close enough watch on them, you can see how much worse they've gotten with time and more partying. You'll want to start refilling their cup with water instead of Coke and rum or beer. Hopefully if they can manage to get that water down, it'll help them sober up. Chances are high that if they're bad enough to fight you on drinking water, they're probably having a really hard time accepting that they're night is probably toast. Don't fight them, just finesse.
UNDER NO CIRCUMSTANCES DO YOU POINT OUT TO THEM, OR ANYONE ELSE HOW BEYOND GONE YOUR FRIEND IS. DON'T BE THAT GUY. It's mortifying, and if your friend is at the point where doing this crosses your mind, chances are that it's going to upset them, a lot. So either they're going to start crying, or try fighting you, depending on the type of drunk they are. You don't want that either.
What you do want is to get them somewhere safe. Get a friend or two to help you walk/carry your drunken buddy over to a couch, bed, or the backseat of a car to get them home. The most important thing now is that they're comfortable, not breaking anything, or themselves. Once they're somewhere comfy get them some more water and a trash can to throw up in if they have to, they'll appreciate it in the morning.
Last, but most certainly not least, take pictures. Take a lot of pictures. You're going to need to document this episode, because the person who's hammered isn't very likely to remember anything from the night before, and they might want to know what got them to the spot they're in now. Not to mention how hilarious it's going to be the morning after to look back on.