On a trip to Kmart for "a few small, inexpensive items," PSFK got what they're calling the "world's longest receipt"-measuring 38.5 inches. Sadly, there are certainly longer ones out there. It's crazy that every time we purchase something we're handed a newly-minted, custom-made piece of trash. Made from paper, no less.If there's anything the internet and behavioral psychology have taught us, it's that smart, small "nudges" can have big cumulative effects. Let's just make receipts available on an "opt in" basis, rather than assuming everyone always wants one. We'd save a lot of paper and ink.