The Joke. Leitz Telyt-V 280mm

Today we not only have huge piles of dirty snow, but it's 51°F so there are huge puddles of melt which have to be negotiated.  I'm sick of it so I'm gonna defy the Blip Police again by going back to September 1, 2013.  This is one of the first digital photographs I ever took with the little Panasonic GX1 using my old Leitz lenses.  We were at a resort on Mirror Lake in upstate New York. 
I've always been intrigued by the dynamic of this group:  I'd say that the two ladies are sisters and the one on the right is married to the dude.  Somehow the ladies look as if they're having a private joke and I would have thought it was on him.  But then, what's he throwing his head back about??