Young girl only one naked at birthday party

Sorry my bad English, not a native language

My friend’s wife, who was a painter, celebrated her 40th birthday. She promised to organize spectacular party, asking guests to arrive dressed extravagant and surprising outfit. „Like carnival,“ she said and added laughing: „If someone wants a special surprise, could also come naked.“
There was one place of lending theatrical clothes and I found hippie outfit from 1960’s and I was quite satisfied. I didn’t think, that I will need some Mickey Mouse or Tarzan outfit, all these ideas were not too much original and I was not going to figure out something extraordinary.
Clearly the most simple solution would have been to come naked, but I left this idea for others. Because I recently haven’t a girlfriend, I had to go alone and maybe this was even better to celebrate loosely at party.
When I arrived, there was also plenty of people, everybody in strange outfit, some of them (but maybe also mine?) not big on special fantasy. But then, five minutes after me arrived birthday girl’s sister and her 14-year old niece. And younger one was really stark naked, even not shoes, as my friend’s wife suggested, when she invited guests.
Maria (name of the birthday girl) was fascinated, as she shouted: „Finally somebody dared to come naked. My congratulations to you, Helen,“ she said to girl and her mom shook her head: „Helen insisted to come naked. I protested until the last minute, but then gave up.“
Helen was gorgeous in her naked „outfit“ and she really felt herself freely, when was introduced to other guests.