When Girl Scout cookie season starts up in your neighborhood, those earnest young saleswomen bearing boxes of sweets may be armed with a new secret weapon: a mobile credit-card reader attached to their smartphones. That's right people. The Girl Scouts have firmly entered the digital age, and our waistlines may never recover. Think of the implications: Before, if you saw a tempting table laden with Samoas and Thin Mints outside the grocery store, being low on cash could prevent you from buying a box or two, or five, or 10. Not anymore.