I've seen this video on opening a beer with a piece of paper many times before, and obviously hundreds of thousands of others have as well looking at the YouTube view tally. But it's still very cool.
When I graduated from college, my two housemates taught me a skill that I had never seen before--opening a non-twist off beer with a lighter. It took a while to master, but that's a piece of cake now. This trick with the piece of paper goes on the same principles, but even folded, the paper doesn't offer the rigidity to make it a simple trick. And I've still gotta do some practice before I can say I mastered it.