We don't know where Joseph learned to "dance" like this (it has a name, "The Morgan," after a sweet little guy we know that did the same thing, though not in front of Joseph), but people think it's hysterical, so he obviously gets a lot of reinforcement to keep doing it.
He did this for more than 10 minutes, just opening and closing the card over and over, until we made him stop because it looks like he's going to break his neck!
This one is more of an overall "happy dance." The boy just loves music! (Hope you like my Mom's singing)
Hope this brings a smile to your face today :)