I hadn't heard a word while I was there, but it looks like there was quite a bit of mischief going on at night. Personally, I was out until 12-1am every night and never saw anything but quiet parking lots with zero activity. Red, Blue, and Purple were common lots I traveled through and I never saw any kids (or young adults). I think there were also issues of theft in Perry, here's the story from Bozeman...
http://www.bozemandailychronicle.com/articles/2008/07/04/news/30flagthefts.txt