Inside the decline of Thinx, the provocative period underwear brand once worth $230 million

(Credit: Nicky J Sims—Getty Images for Selfridges)

Walk into any New York subway station in 2015, and there they were: the Thinx ads.

The striking, minimalist posters featured an image of a blush-tinted halved grapefruit. Crucially, the fruit was not sliced horizontally to reveal the starburst pattern common to brunch tables. It was instead peeled and cracked open longitudinally, creating a suggestive shape.