The noun roisterer is most often used to describe someone who takes his partying too far, creating a disturbance or having too much to drink. You can also use it to talk about loud, boisterous merrymakers, like the whooping roisterers at your backyard barbecue. Roisterer isn't used much these days, but it's been around since the 1600's, from roister, or "noisy bully," with its Latin root of rusticus, "rustic" or "rough country fellow."