Inadvertent (?) exposure of a woman's pudenda, as happened, for example, with disturbing frequency, in the case of several vacuous celeb wannabies (Lohan, Spears, Hilton) during 2007. Common contributing environmental factors are (i) going commando (ii) exiting a limousine.
Given the ubiquity of paparazzi, stalkerazzi, and random onlookers with camera-ready cellphones, the estimated time between occurrence of a gashflash and its photographic documentation across the internet has decreased to less than a quarter of an hour.
Cynical commentators argue that the gashflash, common in 2007, is just the inevitable next step following the many well-publicized nipslips ushered in by the infamous Janet Jackson Superbowl wardrobe malfunction.
Do not think, Mr Justin 'cock-in-a-box' Timberlake, that your overall role in the coarsening of the culture has gone unnoticed. Eventually you will be called to account, and no amount of fancy footwork or soulful crooning will be sufficient to escape retribution.