This is very common. Toddlers are known for their clothing antics. Undressing, redressing, lifting shirts, skirts, dropping pants, all normal. They are learning about dressing themselves and are excited with their new found skill. Not to mention they are excited by thier bodies which are still very new to them. And on top of that this behavior always gets a big response from adults! What more could a kid ask for? While it can be embarassing it is normal and will pass. For now, when she does it, show no emotion. Tell her that it is not ok to take her clothes off unless she is in private and redress her. At home, maybe set aside some 'dress up time' where she can dress and undress as she wishes and if desires be naked for like an hour, then has to get dressed and stay dressed for the rest of the day. Then if she starts to undress again, you can remind her it is not dress up time and she needs to wait for dress up time. And if she does it again in front of guest, just shrug your shoulders and tell your guests 'she's a toddler!'