The Biggest Challenge Facing Musicians at Shows: Audiences Clapping With Bad Rhythm

But when Harry Connick Jr. found himself facing a rhythmically challenged audience, he didn’t need to correct them. At the beginning of this performance of “Come By Me,” the crowd is clapping on the one and three. The claps are tighter than Bieber’s Spanish fans’, but the heavy accents on the downbeats give the music a leaden feel. So, as his solo begins (at 0:41 in the video), Connick throws in an extra beat, realigning the music so that the claps land on the two and four instead. From that point on, the clapping sounds funky instead of square—and the audience has no idea that Connick has wrong-footed them...
http://www.slate.com/blogs/browbeat/2015/11/06/justin_bieber_chastised_audience_for_clapping_on_the_offbeat_the_biggest.html