I don't have any suggestions, just wanted you to know that I can empathize with you since my DD4 does very similar things. She can be so well behaved, but then she gets caught up in the energy of things and can spiral out of control and get wild--not harmful at all, just really silly / wild. She is getting better and I keep hoping she will just grow out of it. Hang in there. It can be embarassing for us as parents.