An audience member at yesterday evening’s xkcd webcomic lecture holds on to one of hundreds of labelled playpen balls which fell from ceiling hatches in 10-250. The label, which says ‘Our hobby: Posting “09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0” in public places,’ alludes to a number of past strips. Randall Munroe, xkcd’s author, gave a lecture on the webcomic to a packed house in 10-250. See page 11 for additional photos.