to give something valuable to someone who does not understand that value: to cast pearls before swine

(idiomatic) "pearls to swine" → to cast pearls before swine

A gold coin of feudal Japan, with a face value of one 両 (ryō).

燃える: to burn; to get fired up / 萌える: to burst into bud; to sprout

to bud, sprout / to be aroused (especially sexually) / (by extension, slang) to feel or experience moé

pearl

a female given name / a surname

cat

a fool, an idiot / uselessness, futility / a tool used for counting coins

foolish, idiotic, stupid, ridiculous / useless, futile