The mildly offensive album art -- essentially, it's a play on the album's title -- disguises the fact that NOFX's punk rock is hardly breaking new ground. Taking the heavy guitar attack of the Sex Pistols and melding it with the us-against-them mentality of mid-'80s American hardcore, NOFX sounds like a conservative punk band with metal leanings. As an expression of adolescent rage, however, Heavy Petting Zoo serves its purpose -- it's basically a barrage of heavy riffs and gut-busting bellowing.