In the days before blogs, teenagers recorded their lives with a pen in top-secret notebooks, usually emblazoned with an earnest, underlined plea to parents to keep away. Since 2002, David Nadelberg has tapped that vast wellspring of adolescent anguish in the stage show Mortified, in which grown men and women confront their past with firsthand tales of their first kiss, first puff, worst prom, fights with mom, life at bible camp, worst hand job, best mall job, and reasons they deserved to marry Simon LeBon.

Following the same formula that has made the...