I did some things like this, but they were often very arbitrary and quite illogical (also, typically very gender based) . Some of it was based on my exposure (cigars are for boy and cigarettes are for girls), and other based on words that were similar (peanuts were for boys... think about it).
I do have a thing with letters and being either soft or sharp that are based exclusively on shape. For example:
Some sharps- X, Y N, M, V, A (only capital)
Some softs- C, B, D, J, a (only lowercase)
some words I classify this way too based on the letters present. Barb is a soft word (even though it is a sharp object). Example is a sharp word (the X tends to trump all other letters).
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