Heavy Metal

Last night I went to a heavy metal concert.  The audience was rocking and swaying.  Their heads were bobbing up and down.  Let me be more specific.  The heavy metal part was comprised of walkers, wheelchairs and canes.  The rocking and swaying was because the entrance to the auditorium was steep.  Heads were bobbing because it was past 9pm and the audience was falling asleep. The concert was at a Florida retirement condo.