Science Times now has an online slide show about science tattoos, here. The author of the piece, Carl Zimmer, long ago did something on linguistics tattoos, featuring a tiny glottal stop (here). A couple of years ago, a bunch of posts on lingua-blogs and elsewhere mentioned other linguistics tattoos, including an IPA vowel chart on the Log (here).
The slide show reminded me, though, that I occasionally hear people talk about linguistics tattoos and other graphics associated with our field. The image here is of a bowling shirt from a bowling team that some UW–Madison grad students started some years ago, The Gutturals. It's the IPA symbol for an epiglottal plosive, a prototypical guttural. (I don't know if they got a lot of gutteral reactions, though, or even guttural reactions.)
So, a question, gentle readers: Aside from t-shirts, what's your favorite image of linguistics in a non-linguistics context?