Anyone familiar with Twitch.tv and the chat system within each stream is aware of channel currency.
It's a point system that the channel offers (each one has it's own rules and name for the currency).
Since I started my stream with a "Matrix" theme, my currency has always been Spoons.
For every 15 minutes someone spends in my chat, they collect 1 spoon.
Viewers can save up their spoons and use them for rewards. Anything from song requests (each song requires 8 spoons), to the ultimate reward: I'll get a butt tattoo (for 1 million spoons).
The most common reward people choose (besides song requests) is the Face Painting! I'm not sure why, but my viewers will save up 4,000 spoons in order to activate Face Paint on stream.
So far I've done it 5 times. Each time, the viewer who is using their spoons gets to choose the design.
I've done: Geometric Fox, William Wallace, Samurai, Sugar Skull, and Neytiri.
It's one of the silly things that streaming allows me to do!