They have been there since before anyone else and they have decent facilities.
According to the Bible, our ancient ancestors Adam and Eve grew ashamed at their nudity in the Garden of Eden after sampling forbidden fruit from the tree of knowledge, and thusly, mankind was forever cursed with a sense of body modesty.
It's not necessary to bare most of your bod to enjoy the evening, but there is a buck off the cover charge reward for those brave souls who decide to strip down or just show up in their undies.