Mismatched and disastrous gigs? I've done a few.
We were a Chicago blues band and the brides father booked us for his daughters wedding. Apparently he thought we were great! We spent the night playing in an empty room and they all stood chatting in the car park.
We played in the Ladbroke, a pub now long gone, every Friday, Saturday and Sunday and brawls just like in a John Wayne western would regularly break out! We were so surprised and shocked at the first punch up we stopped playing. The landlord rushed up shouting, "Keep playing or they'll turn on you!" We played right through without stopping after that.
We were playing in the Officers club on a US Air Base in Germany in 1971 and a Captain got up to sing with the band. He was great. The best voice I've heard but we were fired on the spot. The other officers wouldn't accept him singing with our white girl singer. . . because he was black!! They complained to the club management and threatened us and our gear, ffs!
We were playing the Windsor Castle, Harrow Road and the singer didn't show so the 3 of us decided to carry on. We played a few instrumentals, all sang (badly) and asked if anyone in the audience could sing. A guy in a suit got up and sang a version of Little Richard's Long Tall Sally in the style of Stanley Unwin (Google him). Then a girl got up and offered to do a strip to Green Onions. Well we thought she was a she! He was actually going through gender reassignment and while he had real boobs added still had the meat and 2 veg. That was a very enlightening 10 mins and the moment when he/she whipped off her knickers has stayed with me for the last 40 years.