Hot on the heels of its Wi-Fi detecting t-shirt , the kids at Think Geek have unveiled their Locked ON proximity sensing garb. Powered by 3 AAA batteries, the shirt is constantly scanning for another just like it -- signaling when the two come in range (a few meters) and "locking in" once you make contact. If you're alone in the world (and, let's face it -- clothing like this just might ensure that remains the case), the radar screen on the shirt will be display a persistent "scanning" pattern. We sort of wish we had one of these when we went to raves. Retails for $20 -- hit the source link to order one up for yourself.