WHEN her parents left, Jason and Samantha went to her room to watch Superman. By the time Christopher Reeve was rescuing Margot Kidder from the teetering helicopter, the bedroom windows had fogged up. As it dawned on Jason that this was no drill, that he was about to lose his virginity, he realised with delight that he’d now think of this moment whenever he saw the film again. But then, mere moments after encountering Samantha’s wondrous fortress of solitude, it was over. As John Williams’ score soared, and Samantha sighed mysteriously, Jason lay back and wondered about the definition of irony.