on the spur of the moment
一时冲动地；即时地，毫无准备地
口语·形容一时冲动
英文释义
doing something without planning or thinking ahead; spontaneously
例句
We decided to go on a road trip on the spur of the moment.
典故来源
源自16世纪骑马文化，指用马刺突然刺马加速，后比喻未经计划的冲动行为。