I pull out the "I have a five month old sleeping next door, do you guys mind keeping the volume down?" card. It usually works. (Note: I actually DO have a five month old, this probably won't work if you clearly do not have children)
Since I'm relatively young myself I can relate to the kids that come to a campground to party. I've found that, especially when alcohol is involved, people are oblivious to how their actions are affecting others. The more alcohol consumed, the worse it gets. Sure, sometimes you get that guy or group of people that are ignorant regardless, but in my experience everyone just wants to have a good time and peace can be kept.
In only the most extreme cases have I had to get CG staff or law enforcement involved. I like to try and control the situation myself without resorting to the heavy handed arm of the law. I'd rather be told I'm being a dick by my neighbor than have CG staff or law enforcement come tell me I'm being a dick and I give other people that same benefit.