Henry got this Superman shirt with a velcro-on cape for Christmas and was terrified of it (as seen in this post) until a few days ago.
All of the sudden, he wasn't scared of it, he LOVES it and wants to jump from chair to couch and back while watching "Superman Returns" on TV. To be a three-year-old...
I think this is supposed to be "flexing":
Here he catches a glimpse of himself in the mirror and is momentarily stunned: