For the past four years, Dr. Herbenick has been tracking the rapid rise of “rough sex” among college students, particularly sexual strangulation, or what is colloquially referred to as “choking.” Nearly two-thirds of women in her most recent campus-representative survey of 5,000 students at an anonymized “major Midwestern university” said a partner had choked them during sex (one-third in their most recent encounter). The rate of those women who said they were between the ages 12 and 17 the first time that happened had shot up to 40 percent from one in four.