For a royal party! (Or a medieval fest!)...The girls could wear these, and the boys could wear a king's crown or knight's (faux) headgear... Make them plain and then decorate at the party! ...But do this before age 5 or 6 - children any older than that will probably no longer be interested in this theme!
Just saw this great idea for b day party Make one of these boards and use car sponges (great big ones) fill bucket full of water and then the kids throw I think they would LOVE if it was a hit the parents and then I could see everyone wanting a turn to be hit.