According to recent press reports, Americans are having oral sex at alarmingly younger ages — and with increasing nonchalance. (Note: Oral sex here refers exclusively to fellatio.) Oral sex precedes and often replaces sexual intercourse because it’s perceived to be noncommittal, quick and safe. For some kids it’s a cool thing to do; for others it’s a cheap thrill. Raised in a culture in which speed is valued, kids, not surprisingly, seek instant gratification through oral sex (the girl by instantly pleasing the boy, the boy by sitting back and enjoying the ride). A seemingly facile command over the sexual landscape of one’s partner is achieved without the encumbrances of clothes, coitus and the rest of the messy business. The blow job is, in essence, the new joystick of teen sexuality. In short, if we are to believe today’s sociologists and culture mavens, oral sex has become ordinary. But the increased banality of the blow job is perplexing. When I was a teenager, in the bad-taste, disco-fangled ’70s, fellatio was something you graduated into. Rooted …