石橋を叩いて渡る (ishibashi o tataite wataru: being excessively cautious (lit., knocking on a strong stone bridge before crossing it))
石橋 (ishibashi: stone bridge) stone + bridge
Notice the kun-kun combination here that imparts such a distinctive sound to the expression.
叩 (tata(ku): to strike, beat)
We’ve seen this non-Jōyō kanji once before, but you also probably know its yomi from tataki dishes. Tataki is usually written in hiragana, but since you’re privy to the kanji used, you know that tataki refers to something that’s been pounded—not the fish or meat but the ginger used in the dish!
