I think the worst that I have ever been involved in was on a ship coming out to Australia. We had a concert night and a few of us put together a scratch folk group. We were on early and the spot went pretty well BUT ....We indulged in a beverage or twenty while watching the other acts, then the MC decided to call us back for an unscheduled second spot - we were terrible - it reminded me of the line from Eddie Baker:
There were different tunes in different times and all in different keys ...