話はなしが飛とぶ

expression, godan verb (-bu)

wander off topic; get off track

Used when a conversation suddenly shifts to an unrelated subject, often without a clear transition.

• 彼かれの話はなしが飛とんで、何なにを言いいたいのかわからなくなった。

  His story wandered off topic, and I lost track of what he wanted to say.

• 会かい議ぎ中ちゅうに話はなしが飛とんで、みんな混こん乱らんした。

  During the meeting, the conversation got off track and everyone was confused.