I've been playing the occasional gigs with the band I'm in now for a few years and every concert has been great with decent turn-outs and really appreciative audience who tend to sing along and so on .. More than you can ask for, really! So I've no gig-complaints from the current era of my musicianship.
.. But when I was a teenager in the late 90s, we did some gigs that did not go down very well. We had this electronica group with a stage show that really was all about stuff I'd rather not mention on this site or any other public place; it was pretty awful and all we wanted to do was shock, entertain and perhaps offend. The music was loud and was more or less a mix of chiptunes and electronic acapellas. The audience were pretty shocked at what we were doing. Once we played in a bar and when we were through our first set, we had a break. Some tough guys came up on stage during the break and basically threatened to beat us up. One of them stumped his cigarette in my friends shoulder, but the fight didn't happen. We told the bouncers what was going on, but they didn't throw out the troublemakers. Just as the second set had started and we'd started playing, our sound got cut off and they switched to the DJ. Then we get told to get out
So we were the ones getting thrown out that day.
Another time, there was a local festival and we said we wanted to play with a band just for the hell of it. It wasn't actually a real band with any material, but me and a couple of other guys were making music so we just used some random stuff from our private catalogs. The stage was actually on a small pier in a lagoon so we had some shallow water between us and the audience who were sitting on the beach. One of my mates who is not really a musician at all joined us on stage (why not?) and we were all pretty drunk .. at some point, he decided to wade out in the water and show his junk to everyone. A journalist there thought we were pretty pathetic (we were!) and so our awful gig ended up getting half the press coverage of the entire festival. Of course, the press was pretty negative, but we loved the attention anyways
The hairiest gig-situation I ever read about was Mark Hewins tale about when he played a gig with Soft Heap in a french prison. It's posted on my website, but I assure you this is not a shameless plug; it's actually good reading and highly relevant to the topic.
Link :
A Riotous Gig in a Strange Place | The Polite Force