Check out this genius, low-tech coffee-freshness-monitoring hack

I'm sitting at a general aviation airport lobby in Florida, where my boyfriend's about to fly a plane to carry us somewhere interesting. Here at the FBO, they offer free coffee, which is a good thing for pilots. I saw this on top of the coffee maker, and knew I had to share it with you all. Apparently someone here at the airport reads Reddit. As Rob Beschizza just said over IM, I would definitely pay ten bucks for this on Etsy.