Not really exhibitionist, but I was at a sort of festival, most of us knew each other as we meet up each year there.
Anyway as the evening wore on, and the stories flowed - as did the wine! - I decided to cool off in the sea, which was only about 100yards from where we were. So I stripped off and calmly as I could, walked naked down to the beach. After my swim, I walked back to where the group were gathered, still naked. A few just laughed, some smiled,and a few later on joined me when I again went for a dip! It was odd being the only naked person amongst a group of about 40 people, but nobody was offended, and as I said, two guys and three girls later joined me for a naked swim, though on that occassion we all walked down to the beach and stripped there.
That is my only time that I have ever been the only one naked amongst a group of people.