Remember the old slap bracelets? They could be straight, or you could slap them against your wrist to make a bracelet? Come one, they've revived them with soft edges so kids don't cut their hands open when they are trying to save them from the class bully (happened to me). Anyway, with the new technology of flexible antennas, I'm thinking that a slap phone would be awesome. You talk on your phone, then slap it against your wrist until you need it again. Really handy, right? For the actual article on flexible antennas, check out Wired's Gadget Lab.
Image of flexible antenna via Wired; Image of slap bracelet via the internet