The reaction around the city to the Office of Homeland Security’s new Web Site, Ready. Gov, will no doubt include a certain amount of laughter — and not from nervousness. Whether it’s the “Chemical threat” graphic — featuring a man pondering a chemical attack with his hand on his chin and deceased fish at his feet — or the section informing readers that the farther away they are from a nuclear explosion the better, it’s apt to look a bit simplistic. Indeed, the fact that these graphics are more likely to prompt a smile or a chuckle than a panic or a nightmare is one of the signs of the aplomb and good humor with which New Yorkers and all Americans are greeting the newly tangible risks we face. It’s only a matter of time before these colorful graphics wind up on some Williamsburg residents’ T-shirts. We’re grateful for the distraction, but we can’t help wondering if the effort and money spent on Ready. Gov could have been better spent on making sure the enemy leaders are the ones worrying about their homeland security. That would be the quickest way to make sure that these fallout shelter icons swiftly return to being Cold War relics seen on E-Bay and in dusty thrift shops, rather than at press conferences and trendy boutiques.