About two years ago I was at a meeting in Boston, and my mind wandered a bit during an interminable talks on molecular evolution. I glanced to my left, and noticed that my neighbor was covering a tablet with scratches. Impressed that he was getting so much more out of the talk than I, I peered closer, only to have the scrawl resolve itself into equations.
“Charles” I said. “What the hell are you doing?”
Charles looked up at me with an impish grin and responded “Deriving the equation for paralinear normal distances from first principles.”