Been a lot of years since I've been to one, but the ones I used to go to would usually run out of beer early, and if we were lucky they'd get another keg before the cops showed up and made everyone leave, but that was pretty rare. If the party is in a college town, it might be a little better since people will be less likely to call the police.
I got invited to a keg party this weekend where I can pay $10 for free beer all night or bring my own booze. If drinking from their keg means participating in beer chugging activities, then I'd rather bring my own booze. I just wanna know what a keg party is usually like