When Dave Nadelberg, a writer in Los Angeles, discovered unsent love letters he wrote to a girl he stalked in the 10th grade, he knew they were beseeching, pathetic and solid gold. Inspired, he created "Mortified," a hilarious stage show that is part stand-up comedy and part group therapy, where courageous adults selected from public auditions read aloud from their real teenage diaries, journals and poems about getting French-kissed, fighting with Mom and why they deserve to marry Bon Jovi. Now word of mouth has turned the original L.A. show into a cultural phenomenon: soccer moms and ad execs are sharing the shame in New York, San Francisco and Boston. "Mortified Chicago" will debut this fall, and suburban fans are throwing "Mortified" parties in their living rooms. Presales of "Mortified: Real Words. Real People. Real Pathetic," due in bookstores in November, are already mounting at Amazon. Mortifiers are celebrating "Cringe Night" at Freddy's Bar in Brooklyn and baring their souls at "The Salon of Shame" at Rendezvous in Seattle. Participants, like writer Mathew Harawitz, who aired his transcribed directions for performing Michael Jackson's "Thriller" dance, say sharing a humiliating history is a form of catharsis. "Cringe Night" cofounder Sarah Brown agrees: "It's better and cheaper than therapy."