This teaching device is designed in such a way that it produces an outflow of liquid greater than the amount that is introduced. The idea is that students are to try to come up with a design that will produce the observed behaviour, without knowing what the inner workings of the box look like.

Since the device obviously does not "make water", the name would seem to be fanciful, kind of a joke, expressing what such a device would do if it actually existed: stop droughts.