Darkness falls. The sodium lights wink on. And a young man's fancy turns to thoughts of...impressing the chicks with huge moves in the park, of course. Night-skiing is the perfect teen intoxicant, with all the right ingredients: athletic exertion, speed, risk of injury and an adoring audience (real or imagined). All of it wrapped in the semi-dark-far, far away from any priggish parents-at least until curfew.