Now that Marc Jacobs presidentRobert Duffy has has figured out how to use Twitter , we're having a ton of fun looking at his behind-the-scenes TwitPics of the designer preparing for Fashion Week. A few things we've learned: Marc wears sandals with socks, he's right-handed and he's got some mad guns. We also spied some beigey-gold fabric and an off-white ruffle or two. Take a look: