I met Brian Yap at Adobe MAX this past fall. He was teaching a mobile drawing class in the community pavilion, and I showed up late. All of the iPads had been handed out, and while I always have mine on me, I didn't have any of the files needed to draw what everyone else was drawing. Since it felt weird to walk out as soon as I'd walked in, I used the ten minutes remaining in the class to just sketch Brian instead.
Thankfully he was down with letting me take some reference photos so I could finish it up later. Here is the finished result.