Quicksand Fans

This one is likely to be well known to people from the Boston area and quite unknown elsewhere. However, there are very likely examples of the same thing in other American cities:

Name the only TWO people who performed with the Boston Red Sox, Boston Celtics, Boston Bruins, AND New England Patriots.

The answers are John Kiley and Rene Rancourt. Both played the national anthem before games for all four teams although mostly for the Bruins in the case of Rancourt and the Red Sox in the case of Kiley. Kiley played the organ and Rancourt was a singer.

I would not be surprised if there have been similar cases in other major cities but I happen to be originally from Boston. I have been in attendance several times when Rancourt sang but I think I have heard Kiley only on radio and television and not live.