灵机一动

词典解释

[bright idea occurs;be seized by a sudden impulse;have a brainwave; flash through one's mind; when the maggot bites] 突然想出个好办法

他灵机一动,撒了一个谎。——周立波《暴风骤雨》

成语解释

灵机：灵巧；灵活的心思。形容灵敏机智；突然想出办法或主意。