Proof that reality television can erupt anywhere and anytime can be found on “Instant Beauty Pageant” (9 p.m., Style). Hosts Cameron Mathison (“All My Children”) and Debbie Matenopoulos (“The Daily Top 10”) scour the malls of America to find unsuspecting women to participate in an impromptu beauty pageant, complete with tiara and fairly major prizes.

Would-be stars are dragged from photo booths and procured from cosmetic counters and asked to spend the next three hours shopping for a bathing suit and gown and to undergo a hair and makeup session and prepare a “talent” show on the fly.

Mathison and Matenopoulos deserve credit – not just for their spunky promotion of this preposterous proposition, but also for casting their show so strategically. Tonight’s competition takes place at a gigantic shopping emporium in Virginia Beach, Va., and includes a wallflower, a tattooed fashion victim, an extrovert who has spent far too many of her 36 years screaming over the bar band, a shy woman and a wretchedly spoiled mall rat.

This last contestant makes the pageant worth watching. You can’t have a Cinderella without a wicked stepsister, and she provides the perfect villainess. She claims she was born to shop and that the first word out of her mouth was “Mine!” Whether bragging about her beauty and exhibiting a disturbing self-regard for her own breasts, browbeating shopkeepers or scheming to cheat the other contestants, she’s deliciously hateful and delusional, to boot.

“Instant Beauty Pageant” may be forgettable fluff, but it proves that sometimes it takes the presence of a camera crew to allow someone to reveal her true colors.

¢ Long a network fixture and frequently aired on Thanksgiving and Christmas holidays, the 1965 musical “The Sound of Music” (6 p.m., Family) moves to cable to run on Good Friday and repeat on Easter Sunday. With the exception of a one-time airing on AMC some years back, this marks the first time “The Sound of Music” has appeared on cable television.

¢ New York police Detective Jerry Palace leads the investigation on “The Investigators” (9 p.m., Court), a weekly series exploring cases in which serious doubts have been raised about the evidence used to achieve convictions.

Tonight’s episode looks at the case of Darlie Routier, a Dallas mother sentenced to death for murdering her own children. She claimed she fought with the real killer, who escaped but not before claiming the lives of her sons. Palace gets the first interview with Routier’s husband and talks with several other players to see whether the wrong man, or woman, is sitting on death row.

¢ The Sci Fi Channel unleashes a seven-episode “Stargate SG1” (7 p.m., Sci Fi) marathon.

Tonight’s other highlights

¢ Nothing ruins a date like the malingering spirit of a dead ex on “Ghost Whisperer” (7 p.m., CBS).

¢ A mother’s testimony may doom her son on “Close to Home” (8 p.m., CBS).

¢ Raines’ new “ghost,” a murdered 20-year-old drug dealer, had another, softer side on “Raines” (8 p.m., NBC).

¢ “Shut Up! It’s Stacy London” (9 p.m., TLC) features talk about fashions.