So, we were working on playing with the ball in his stand-up toy (if he puts the ball in the hole and pushes it down, it drops down a tube to the bottom of the toy).  And, then I started trying to get him to “fetch” the ball as it went away.  He thought this was absolutely hysterical as you can see here:

Also, he thinks it is hilarious to stick his fingers in your mouth and get them (gently) nibbled on.  🙂