Adorable!
If you have a stability ball, working on having him put his paws up on top and balance like that can strengthen his core which can extend the hold of sit pretty. There are ones designed specifically for dogs so their nails don't puncture if but I just use my Gaiam ball and haven't had a problem yet.
Honey loves doing this...he'll walk all over the basement with it-but only for my husband. It's the one trick he reserves for doing only with him, if I try I get a bark and she just attacks it.
