At 6'8", I have heard this joke enough times to make me a millionaire at a nickel per. Nevertheless, I now have an answer: a fiendish grin. My current project involves the weather. Which means I need to take a crash course in meteorology and the weather. One thing I love about writing is that I'm always learning. One of the things I hate is I'm always researching. Mostly because I get sidetracked by the former.
It's an easy thing to be researching then suddenly go "Oooo! That sounds cool. Time to read up on this." Click. Many an hour has been lost in what should be a quick bit of research. But at least I'm entertained and learning; and I still get my writing done.