Sumner Redstone moved closer to the stage, transfixed. A nude couple on a Harley-Davidson had just descended from the ceiling of Super Girls, a Bangkok sex club endorsed by Rolling Stone as “the very best in town.”

Redstone, then 72 and chairman of Viacom , stood “like a deer in the headlights, mouth slightly agape,” writes Tom Freston in his new memoir, “ Unplugged: Adventures from MTV to Timbuktu ” (Gallery Books, out now). The media mogul was rapt as he watched the couple have sex on the bike while the man gunned the throttle.

At the time, Freston was the MTV Networks CEO. Touring his boss around Thailand’s illicit offerings wasn’t in his official job description, but when Redstone announced plans for a 1995 Asia trip, he’d quietly asked: “Tell me what you know about the sex clubs

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