I just came across this term in The Upstarts, by Brad Stone, loc 1828:
Enjoying a modicum of momentum, Kalanick leased a new office in San Francisco but had a month before he could move in. Instead of waiting, he took the whole company to Thailand, where they worked eighteen-hour days out of cafés and a house overlooking the craggy Railay Beach coastline rewriting the Red Swoosh code. It was a productive retreat and the first of what Kalanick called workations, a tradition that continued at Red Swoosh and, later, Uber.
There are loads of videos on YouTube about this:
(the last one is particularly cringe-worthy)