I took this photo of my baby girl a week ago on Easter when we were waiting for my youngest to get ready for Easter egg hunt in our back yard. I asked her to look at me, and I got this sort of fakish big grin from her. I always either get that, or a grumpy face, a little bit depending on her mood. I can vouch, though, that she was genuinely happy here despite the fakish grin, since she was super excited about the egg hunt.
(85mm, ISO 200, f/3.2, 1/200 sec)