Oh, of course I know it exists and have often witnessed it. But it's quite some time since I witnessed any kind of obnoxious drunken behaviour *in* a pub.
Having said that, a couple of weeks back I saw a lad pass out in a fairly genteel pub on Saturday lunchtime because presumably he'd been on a bender into the small hours. They had to call an ambulance - which is something I've never seen in a pub before!