What's a scuba smile?

It occurs to me that I have not explained what exactly a scuba smile is to me.  In almost every dive, I throw out my arms wide, cross my ankles, toss my head back with my eyes closed and smile through my regulator.  It is my absolute favorite thing to do.  Even if it's in an 8 foot pool.  The best scuba smile is doing so through someone else's bubbles.