Have you seen those Wi-Fi detecting T-shirts before? Well, the folks over at Instructables have come up with a way for you to turn that into a Wi-Fi detecting bumper sticker. It would certainly be more practical to keep it inside your car (so that you know when there is a Wi-fi signal), but you could always stick it facing outwards at the back of your car (as pictured), so the person behind you knows that there is Wi-Fi, though it seems like a waste of effort. You’ll obviously need the Wi-fi detecting T-shirt, and also a bunch of double-sided tape, and 12V to 5V USB car adapters. If you decide to do this, have fun, and let us know your feedback via the comments section.