How you can cash in on the cofounder of Twitter’s latest great innovationCafé Grumpy, a renowned New York City coffee roaster with four locations in Manhattan and Brooklyn, tends to do things differently. Everything from the frowny-face logo to the $12 cup of coffee to the unique pour-over brewing techniques makes it apparent Café Grumpy is not your ordinary coffeehouse. This do-things-differently approach extends to every aspect of the Grumpy experience, even to their cash registers. In fact, they don’t have any. All you’ll find at the front counters are iPads with an attachment from a company called Square.If you’ve ever swiped your credit card through a tiny white attachment atop an iPhone or iPad, then you’re familiar with Square, the ­latest endeavor from Twitter cocreator Jack Dorsey. What began as a way to accept payment for services over the phone is rapidly evolving