I remember a guy at a Tegan and Sara gig that heckled the support act and tried to get me to boo them too (when I actually liked them enough to buy an album), then proceeded to heckle T&S too, start a fight, punch/get punched, make T&S stop the gig to shame him and then get him thrown out. Which was really pretty impressive in it’s own way, what a good use of £20 and a couple of hours …