There's an argument out there that oral sex is not sex. For some grown-ups, it's a way to deny that they're cheating. To some young people, oral sex preserves virginity—technically speaking—and allows for what is perceived as risk-free sexual intimacy. From a medical perspective, however, this is sex—and generally, as practiced, it's unsafe. People seem clueless that sexually transmitted diseases such as herpes, gonorrhea, chlamydia, and human papillomavirus can take hold in parts of the oral cavity during sex with infected partners and that the oral contact can infect the genitals, too. HPV is a particularly scurrilous threat, since it...