You never know who is going to show up and join Billy Joel on stage for his monthly concert at Madison Square Garden.
You also never know where Bruce Springsteen might show up.
Well, it happened last night. Bruce showed up for Billy Joel's 100th sold out show at Madison Square Garden and sang two songs with the Billy...
Talk about iconic: the Piano Man and the Boss, together at the Garden. Here's a look at the 2 songs they jammed together, to help celebrate Joel's big night.