I read this somewhere on these boards and it is cute! When I want my kids to put everything down and look at me, I chant "Hands on top" while putting my hands on my head. They respond "Everybody STOP" while putting their hands on their heads. It works well, because they can't put their hands on their heads and hold crayons, pencils, etc.. at the same time.
I also like "Hocus, Pocus, Everybody Focus" I read that somewhere on these boards, too, but I haven't used it yet. Maybe this week I'll try it!
Have a great week!