Worst; Pink Floyd at the Stadium around 69-70. We all went for a Rock Concert (at my Instigation tbh, as I wanted to see The Floyd...the See Emily Play Floyd.)
They were on with others, not on their own or headlining, seems, with hindsight, they were trying out the 'New' post Barrett - pre Atom Heart Mother stuff...all too new for us.
They did 2 and a bit songs...'long' songs for the time not your 3m 20secs pop stuff...Then stopped...somebody? Waters? said, it's not working is it.
Unplugged from his amp and lead them all off.