Thai people put powder on the face of a police officer on a street in Prachinburi Province, east of Bangkok, Thailand, on April 13 to celebrate the Songkran festival, Thai New Year.
Yeah, I don't get it either, but apparently the Songkran festival is simply massive. It's the Thai new year, lasts for several days. When I googled around I found that the festival is all about water, not powder; the last day is water-splashing time, and you can't go outside without getting hit with water, splashed, squirted, etc.
Apparently people are learning to put their cellphones in condoms during the festivies, so they don't break when they get wet.
More Songkran. mostly from
here: