Dear D.,
I know - but you did catch me laughing - My gr grand daughter did it too, she even ran outside one time like that. We caught her right away,it was embarrassing, and sort of scary. But 'they' do it. I don't think that she will do it in public though.
Give her a certain time of the day when she can do that - like just after her bath. My daughter, the grandmother now of the nude beauty in our family - invented running around the house without clothes on after her bath. It was easy to catch her and put on her pajamas, then book and bed. So I don't have any ideas to help you. Just to let you know it has happened in two generations in our family.
I know that her brother used to squirm when he had on a tee shirt that was itchy on the inside. So check on that.
My daughter took all of her clothes off down to the panties and socks when she went with us to register her brother for Kindergarten. I do know that it was an itchy dress then and that soon had to not be used anymore.
I don't know....kids do that. Maybe you could bribe her. It is o.k. to bribe kids IF they keep their side of the 'contract' or bargain. But they don't get 'paid' unless they leave their clothes on or whatever is the behavior that you want to change.
C. N.