It sounds like a "Playful Parenting" sort of thing to do...and that's always a good thing (in my opinion, anyway).
Now, I don't have children your children's age, so consider that while you read this response.
As long as they are having fun, giggling, enjoying it...then I would say keep it up. Let them enjoy it.
If it ever gets to the point of becoming a punishment (example: "I said 'get your hands on your head and KEEP THEM THERE!'"
), then no, I wouldn't be cool with that.
__________________
"Nobody knows what we're for only what we're against when we judge the wounded.
What if we put down our signs, crossed over the lines, and loved like You did?"
~Casting Crowns