Sorry to give a serious response to a light-hearted item, but the mezuzah derives from an attitude that is quite different from that which looks to magic charms for protection.
The source is Deuteronomy ch.6, which exhorts us to love God by doing "right and good" things, and by keeping His commandments in mind. Verse 6 says that they should be "in your heart" (Hebrew idiom for mind). Verse 7 says that they should be contemplated throughout the day and at bedtime, and taught to children. Verse 8 says that they should be "upon your hand" and "between your eyes", while verse 9 says to write them on your house and gates.
Unfortunately superstition led to literal, and ultimately magical interpretations of verses 8-9, resulting in the practice of actually wrapping one's head and arm in leather strips to which Biblical writings are attached (tefillin), as well as the mezuzah. Perhaps if they had been more adept at open-heart surgery they could have done the same for verse 6. On the other hand, verses like Exodus 13:9, which also includes the hand-and-eyes language, tells us to keep the words "in your mouth"; and no Jews, so far as I know, walk around with a jaw full of Biblical pages.
By the way the Karaites and Samaritans, two Jewish sects that reject the Talmudic interpretations of the Bible, make a point of ridiculing the tefillin. They say that the hand-and-eyes language is just telling us: read the book, dummy! (And by the way, read the whole thing, not just some scraps that fit in a tiny box.)
What I'm saying is that if you read the text without being completely metaphor-blind, there's a pretty simple message: to think about and discuss moral issues, making them your top priority in life. Help the poor, love your neighbor, blah blah blah. It isn't rocket science, and neither is it magic.