Unfortunately not 2016, but two years ago when the Samsung Gear Watch came out a friend of mine got it right away. We went out drinking the same day and when we came back at night we put together a watch face while still being drunk. We uploaded it, set the lowest possible price 1$, and... Nothing happened. Everywhere in the admin panel it showed 0. 0 downloads, not a single dime earned, even after a few days. We were devastated.
But than I found another tab in the utterly shitty admin panel and it hit me like a rock. The numbers on the dashboard were a monthly overview and in fact we earned already hundreds of dollars and downloads in just a few days. I went back to the computer, but together an even better watch face, set it to 1$ again and watched it selling like hotcakes.
However it tried out quite quickly after that. People started to copy stuff and giving it away for free and I never bought the watch myself, I just used the emulator to test my apps. So I took them out of the store at the end because dealing with taxes and sharing the income does not make it worth it if you get support requests like "how can I change the time on my watch", "what do I care, its your shitty watch and Samsung's shitty interface"...
So yea. That's my best story about unexpected passive income. Selling stuff fast on a new platform seem to work!
Edit:
Found some screens.
First one: https://i.imgur.com/TIVsPKO.png
Best selling one: https://i.imgur.com/9L8TetO.png