Back to the Future II Marty McFly Hat
"Pull out your pants pockets. All kids of the future wear their pants inside out." - Doc Brown (Back to the Future: Part 2)
The future world of October 21, 2015, as predicted by Back to the Future Part 2, hasn't happened yet, but since the cool new Back to the Future II Marty McFly Hat now exists, the possibilities of hoverboards, auto-lacing shoes, flying cars, self-drying jackets, food hydrators, Mr. Fusion and a World Series Cubs win are now closer to reality (disregard this post if reading it from the future and it's all wrong).
This cool cap is an exact replica of what Marty wore on his time traveling trip to the future and uses the same bizarre ultra-refractive material that shimmers and changes color in the light. Sure you'll look like a butthead wearing it now, but not for long...