FOR months, a mysterious man known as "Poster Boy" has been altering New York City subway advertisements with razor blades. He cuts noses, ears and words off of ads and then re-attaches them to other ads, sending hilarious and sometimes scandalous messages. According to The Guardian, he works only on empty platforms and avoids areas with CCTV cameras. Last week, however, New York City police arrested the suspected Poster Boy at an art exhibition in SoHo. They identified him as Henry Matyjewicz, although some doubt that he is the real Poster Boy. His presence had been announced in a flyer that billed him as an artist who "[remixes] and recreate ads that bombard us in the subways into politically charged social commentary." In one example, Jamaican sprinter Usain Bolt's Puma ad is transformed into a McDonald's ad. The headline reads: "McDorse the world." Before the arrest, Poster Boy had justified his work to The Guardian: "I want ‘Poster Boy' to be about... taking your environment into your own hands and making it what you want. As long as you're not hurting other people, it can't be bad." The NYPD obviously begs to differ. Examples of Poster Boy's work can be found online at "www.flickr.com/photos/26296445@N05/".