This summer, after I had amassed a delightful collection of geeky t-shirts, I was promoted to a managerial position where I couldn't really wear them to work. My solution? Design geeky fabric, print it at Spoonflower, and sew it into button-down shirts.
I started with a design based on birchbark letter 206, the 13th century drawing of a young boy named Onfim. It turned out quite well, though the downside was that Slavic conferences are the only environment where people recognize the pattern if you point it out. For my second design, I went through every single xkcd ("a webcomic of romance, sarcasm, math, and language", by Randall Munroe, and my absolute favorite comic), from #812 until #200, and extracted and arranged the figures. It's not for sale in the Spoonflower marketplace, due to the non-commercial provision in the Creative Commons license that xkcd uses, but anyone is welcome to download the pattern and print it for their own non-commercial use.
I've worn the shirt to work a few times already, and the results have been interesting. I sit and have long conversations with people who I know are fans of xkcd, and they don't even notice until I finally point it out. Maybe after three years of looking at graffiti, I overestimate other people's inclination towards noticing the small things around them, but it took me by surprise.