The Locked ON Proximity Sensing t-shirt is a stone cold radar-detecting piece of apparel. When separated from companions, its radar screen stays in scan mode. But get within a few meters of another Locked ON wearer? Target detected, baby.
The decal on the front of the shirt is removable, since you probably wouldn't want to wash it, and runs on three AAA batteries. Its radio frequency transmission/detection range is about three meters, so chances are your eyes will spot a Locked ON compatriot before your radar will. At least, though, everyone around you will know you two were made for each other—or at least, your shirts were. [ThinkGeek via Techeblog]