I was at one of the early Great Escapes, and they had some a lineup of some of the arty post-punk smoke machine type bands in the bar on the pier. One side was the gigs, the other side continued as a karaoke bar. However the two sides shared toilets, and the doors out were identical.
So loads and loads of really pissed people on stag and hen dos standing watching the bands for a bit, really confused until they realised they’d accidentally got into a different room.