Well this is just awful...
Sir Elton John had just invited some people from the front row of his concert on stage to watch the show, and one of the fans threw some beads at him!
As you can see in the video, he is stunned, and looks like he thinks something happened to his teeth.
It took him some time to regain his composure, and then the show went on, but looking like he won't be bringing his front row on stage again any time soon. :(