Cheap GPS
Cheap GPS
[Cueball driving down the road, with a GPS reading "COLD."] GPS: COLD... WARM... HOT! COLD...

GPS is a system allowing people to find their location and from that, speed on Earth. It was first developed for the U.S. military, but now it sees international usage for everyday navigation. Many motorists today have GPS devices (sometimes just called GPS's) that can give driving directions electronically.
Hot and Cold is a children's activity/game where one person searches for an unknown object, and the rest must respond "Hot" or "Cold." Other words, such as "warm" and "cool" can be used to describe their distance more accurately. The closer the player is to the mystery object, the "hotter" they are.
This GPS would be extremely difficult to use, as it gives no directions, only telling you how close you are to reaching your destination. The series of instructions spoken ("cold," "warm," "hot," then "cold" again) suggests that Cueball either missed a turn, or that he just passed his destination.
Randall describes a past engineering project of his that can only describe turns "as the crow flies." So, for example, if he was driving north with the destination to the northeast, the GPS would tell him to turn right even if no such turn was legally possible. Perhaps not very functional, but it is a pretty cool thing to build.
While cars go fast and are only allowed to, or able to, use a very limited number of all roads and trails in the world, this is less so for pedestrians. As a consequence, for hikers, an app that just shows the direction you should be walking in 'as the crow flies' is actually quite a common and useful tool, since a lot of small roads suitable for pedestrians do not show up on maps. Of course, just printing 'left' or 'right' is much more primitive than showing an arrow in the correct direction (compass-like), and often less helpful since on one cross section there can be multiple trails to the right.
[Cueball driving down the road, with a GPS reading "COLD."] GPS: COLD... WARM... HOT! COLD...
