"IF THESE HALLS COULD TALK," TONIGHT ON ABC'S "20/20"

School is finally out, but do you have any idea what your teens are doing with their free time? Anchored by Elizabeth Vargas and David Muir, "If These Halls Could Talk" airs on "20/20" TONIGHT, FRIDAY, JUNE 28 (10:00-11:00 p.m., ET) on the ABC Television Network. Reports include:

Slut Shaming: One morning in April, nearly 1,000 students sat listening in an assembly -- some in disbelief -- as a provocative, Christian guest speaker preached in their public school about abstinence. But the tone of the lecture was considered so aggressive that one 18 year-old honor student gave it a very loaded label, "Slut-Shaming." Speaking out in protest turned this once popular West Virginian high school senior into a pariah in her conservative town. It's one girl's crusade against her community. Elizabeth Vargas has her story.

Don't Try This at Home: MTV reality show "Jackass" had a tagline: "Don't try this at home." Unfortunately today's teenagers are not heeding that advice, as an alarming number of dangerous, sometimes deadly, self-injuring stunts are all the rage on the internet. As if the rush of a cheap thrill found while hill-hopping or car-surfing is not enough, they're turning towards new and inventive ways to get high. Dan Harris talks to some daring adolescents and a teenage behavior expert, providing a cautionary tale for any parent who thinks, "My kid wouldn't do that."

Who Needs College?: While most people look at the acres of parking lots at major airports and only see cars, Rajul Zaparde, 18, Kevin Petrovic, 19, and Shri Ganeshram, 19, see something else: money. So they put their college plans (MIT, Harvard and Princeton) on hold to create a business model that is giving established car rental companies a run for their money. Chris Connelly talks to the brains behind this venture, and to a San Francisco city official who's not patting them on the back -- he's taking them to court.

Rich Kids Instagram: More and more, wealthy teenagers are using photo sharing site Instagram to pull back the velvet curtain on the world of the ultra rich. As Nick Watt reports, this isn't a manufactured reality show, rather real kids giving a glimpse of their excessive, fabulous lives. And "regular" people can't get enough.

Sex Change Sweethearts: Katie Hill, 18, and her boyfriend, Arin Andrews, 17, are crazy in love. They're like any other teenage couple except that they were each born the opposite sex. Arin was born a girl and Katie was born a boy. Before they transitioned, each endured years of bullying, isolation and thoughts of suicide. Now Katie and Arin are happy and enjoying life for the first time with someone who completely understands how it feels to be born in the wrong body. Deborah Roberts reports.

David Sloan is senior executive producer of "20/20" and John Green is the executive producer.