h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I would invent batmans grappling hook. i could travel faster by flying up the sides of buildings instead of using the stiars or elevator. I could escape some messy situations. I would have used it at the concer i went to last week so i could get on those seats near the ceiling instead of just standing with the rest of the crowd 300 feet back. wouldn't that be great? i know some physics, so maybe i could make one. id require some really strong metal wire, a grappling hook that could sink into rock and a firing device that would fit in the palm of my hand. wouldnt be too hard. might be my summer project as i have nothing better to do.