Adolescents have always found creative ways to keep mothers and fathers pacing the floor at 2 a.m.

But teenagers can't be blamed for at least two parental nightmares - rainbow parties and sex bracelets, according to sociologist Kathleen A. Bogle.

These technicolor horrors, which first gained wide publicity in the early 2000s, are largely figments of adult imagination - the spawn of an unholy marriage of fear and rumor, Bogle said during a recent interview at her office at La Salle University.

"What everybody 'knows' is often not true," said Bogle, coauthor of the recently published Kids Gone Wild: From Rainbow Parties to Sexting, Understanding the Hype Over Teen Sex (NYU Press).

At a rainbow party, she explained, a series of girls, each wearing a different shade of lipstick, supposedly perform oral sex on boys who then proudly display the lemurlike rings like a trophy.

And sex bracelets, also known as "shag bands," she said, are ostensibly color-coded contracts, each one signifying a different sexual act that a girl will perform for anyone who yanks the rubber wristbands off her arm.

In their research, Bogle, a sociology professor at La Salle, and her coauthor Joel Best of the University of Delaware could not find any confirmed reports of these sexual games.

And yet the anxious chatter continues, years after the rumors should have been put to rest.

"Urban legends are about underlying fear," said Bogle, 40, whose previous book, Hooking Up, examined the college culture of dating and sex.

While it is impossible to prove that these activities have never happened, she and Best wrote, "at the very least there is no evidence that these forms of sexual play are at all common. In other words, it seems likely that far more people talked about these phenomena than ever engaged in the sexual acts described in the stories."

Sociologists have known since just about forever that adults are destined to worry about the younger generation's bad behavior, said John Santelli, chairman of the department of population and family health at Columbia University.

"As we all get older, adolescents seem less well-behaved than we think we were," said Santelli, 62. "But the changes are in our perceptions, not in reality."

Back in the primordial days when Elvis Presley's pelvic gyrations scandalized parents, the musical Bye-Bye Birdie featured a song with the line "What's the matter with kids today?" that summed up intractable parental hubris in a single sentence:

"Why can't they be like we were, perfect in every way?"

The truth is that today's teenagers are having safer sex, fewer unwanted pregnancies, and holding on to their virginity for just as long, if not longer, than previous generations did, Santelli says.

The Centers for Disease Control and Prevention's National Survey of Family Growth, found that over the last twenty years, the percentage of girls 15 to 19 years old who had sexual intercourse has fallen from 51 to 43 percent. Among boys, the rate has dropped from 60 to 42 percent.

The average age when teenagers have sex for the first time is 17, and has remained fairly constant for decades. Fewer teens, however, are having sex younger than that, and a great majority have become significantly more responsible about sex, according to data compiled by the Guttmacher Institute, which studies reproductive health. In the 1980s, the institute reports, fewer than half of teenagers used contraception the first time they had sex. Today, 78 percent of girls and 85 percent of boys do.

According to the National Center for Health Statistics, since 1970 the teen birthrate has dropped 57 percent.

Teenagers do think of oral sex less seriously than their parents and grandparents did, Bogle said, "but it's a big jump to believe that "Snap off a bracelet and they will do it for anyone.' "

Urban legends such as this provide parents with an opportunity to indirectly express their fears, said Bogle.

"When you ask, 'Have you heard of sex bracelets?' it's a way to talk about how another kid is going to corrupt yours."

Politically, these stories appeal to both sides, she said. "They fit the agendas of conservatives who say the nation is in moral decline, and of liberals who say women are being exploited."

One of the dangers inherent in these urban myths regarding sex is that "they don't just linger in our own minds," she said.

Teenagers and young adults often compare themselves to what they believe to be the norm and adjust their behavior accordingly, Bogle says.

So when they are led to believe that "everyone" has had sex by the time they get to college, they feel pressure to conform. The reality, Bogle says, is that one in four college students ages 18 to 22 is a virgin.

"So you are making decisions about getting rid of your virginity based on a false assumption."

Bogle and Best analyzed the trajectory of isolated rumors about teenage debauchery to major network coverage on the evening news and found that few reporters took the time or effort to investigate the facts.

Each time the public hears "Coming up at six: shocking news about the bracelet your kid is wearing," in the same breath as substantive reports about the Middle East and the economy, she said, the bogus stories gain credibility.

And once they take hold, she said, they are very difficult to shake.

"The idea that the things kids do today is a disgrace is so ingrained that it is hard to talk people out of it."

Where solid sociological research fails, logic may succeed, particularly regarding the rainbow parties. As skeptics that Bogle and Best found on social media pointed out, even if boys had the stamina to sustain such a series of performances, the lipstick would not.

"No," one astute observer wrote. "The practicalities of this don't work out."