ねこ小判 こばん
nekoni koban

Idiomatic Expression

1. casting pearls before swine; (giving) a gold coin to a cat — literal

Related to 豚に真珠
きみのせっかくの めい講義 こうぎ ねこ小判 こばんだったね。
kimino sekkakuno mēkōgiwa nekoni kobandattane.
Your wonderful lecture was pearls before swine.
Other forms: