Illegal public art is in the news. The most notorious instance this summer was the switch of flags on the Brooklyn Bridge, by two German artists, from the Stars and Stripes to all-white versions of the same. Others include a Canadian artist’s scrawls, partly in blood, on a wall in the Jeff Koons retrospective at the Whitney Museum and, in Moscow, the painting of a star ornament atop a Stalin-era tower, in Ukrainian national colors. Internationally, the British midnight muralist Banksy continues his waggish depredations, rivalled of late by a female upstart called Bambi, who likewise stencils images, only with a sexy-feminist spin. The over-all phenomenon could use a name—I propose Stunt art—and some analysis, starting with distinctions.