To hit someone's 'sweet spot' — to exactly fit someone's taste or sense of humor; to get a great laugh or reaction.
そのギャグは彼のつぼにはまって、みんな大笑いした。
That gag hit his funny bone and everyone burst out laughing.
新しいデザインが彼女のつぼにはまったらしく、すぐに買った。
The new design seemed to be exactly her taste, so she bought it immediately.
この映画は若者のつぼにすっかり嵌まったようだ。
This movie seems to have completely appealed to young people.
To go as planned or to succeed as expected; for a plan or method to work effectively.
作戦がつぼにはまり、一気に得点を重ねた。
The tactic worked perfectly, and they quickly piled on the points.
宣伝のターゲットを絞ったのがつぼにはまったらしい。
It seems that narrowing the promotional target paid off.