The Dead Milkmen, a Philadelphia quartet known for their quirky underground hit singles such as “Punk Rock Girl,” “Dean’s Dream,” and “Stuart,” spent years making an art form out of not taking things too seriously during their late 80’s heyday. Twenty years later, the world hasn’t forgotten them. There could have been little more proof of that than the string of sell out crowds at the sporadic reunion shows they’ve played since November 2008. On…