If you take a closer look, the cleverly designed box compares your shoe size to other things. If, for example, you’re an infant size 5 then your foot is the same size as a blues harmonica (see the side of the box picture below).
A wee bit bigger than an infant?
If you’re a men’s size 15 1/2 your foot is the same size purportedly as a gangsters’ gold chain (see second picture for more comparisons).
This is a great example of relating something known and familiar (your feet) to something new and creative.
It changes your perspective of your feet by comparing what you know and are (presumably) comfortable with to something novel.
When you’re introducing a new concept, especially one that you think may be unwelcome or feared, start with what’s known and familiar.