"White over red" isn't actually possible unless the VASI installation is badly off, or else if you're upside down on final. If the top lights are white, you're above their glidepath angle, and if the bottom lights are red, you're below theirs. With a standard VASI installation done correctly, you can't be in both places at once -- if you're above the path for the upper lights, you're above the path for the lower lights as well, and vice versa.
The "white over red" is simply a nonsense answer thrown in to some test questions in order to see who understands what's going on with a VASI system. Most folks will remember that when you're on the proper glidepath you'll have one set of red lights & one set of white lights, but which one should be where? As long as you understand how the lights work, you can correctly answer that red above white = on glidepath.
My best guess at the mnemonic is that they're suggesting you're "standing on your head," or in other words upside down, in order to see the lights in that position. I wouldn't get too wound up about the lame rhyme in the memory aid. Just know that with all white, you're high; with all red, you're low, and with red over white, you're on path.