Playing Dead

For some reason Justin likes to crawl around and then all of a sudden fall down to the ground as if he is playing "dead."

Then he'll pop up to see if anyone is watching him.

And it seems like he knows I like it when he plays "dead" because he went right back down for me to get a picture of him. I'm trying to teach him to fall to the ground when I say "dead" but it isn't working too well.