I brought that friend unfortunately this year. Had an amazing camping group, most of us were always happy to see each other roaming in the fest and meeting up here and there with a good number of the group was always a great time, and the pre and post fest parties were always a nice touch. I brought a co-worker though that I made a decent effort looking for a ticket and she eventually found which I thought was cool, but it turned out to be the start of a nuisance. First off, she avoided the rest of our camping party like the plauge, I brought another co-worker and his gf and they got along swimmingly with everyone but this girl could just not socialize. She was also completely inept for some reason, basically asked me for everything, making her drinks, food, asking for anything that might be in one of my friend's sites, it was incessant. By the second day I flat out told her that she can make her own damn drink, I have dreams too!
She also would not stop trying to bring me to her aunt's house a couple miles away for a shower and rest up in the middle of the day. I appreciated the first five offers but she for some reason could not understand that I was afraid that I'd miss music that I have been looking forward to for months as opposed to some shower, and lo and behold, the day she went she wasn't back at the campgrounds until four. It was at this point I just turned my phone off, I couldn't stand the constant calls and "Where are yous?" being texted to me while in the middle of a great show.
The worst part though was that even she only drank the entire weekend, and was considerably less intoxicated than the rest of us who had more diverse taste in intoxicants, she was still the most belligerent every single night! Passed out cold in a neighbor's chair every single night, completely helpless, and she even broke my gf's tent's zipper getting into it one night! /rant
On the other hand someone in my group brought a true mystery friend, (seriously the guy just turned up to our site on the first night and his one connection to us was passed out) this guy was a perfect fit though and got along with everyone.