UTZ, Fla., June 12 — On the third-to-last day of summer camp, the temperature has risen to 98 degrees, and even the troupers have begun to whine. "I don't want to play strip volleyball!" complained Jane Jeffries, 13, her sunburned shoulders sagging. "I want to play regular volleyball." Halie Nelson, 14, agreed, "Yeah, I'd rather get all the clothes off, and keep all the clothes off."