...is that if you look at them, the definitely look back at you.
You keep looking and then they look back. And then you spend time smiling making faces, and making baloons with your cheeks and doing things with your hands. They look away. And then you keep doing it. They look back to check if you are still doing it. And you do it a bit more and smile a bit more.
and .. ... .... then .. .. they smile! :)
And you SMILE your heart out! :D You have just had one of the most beautiful experiences of the day!