What is another word for build a fire under?
Pronunciation: [bˈɪld ɐ fˈa͡ɪ͡əɹ ˈʌndə] (IPA) 
When you want to motivate someone to get moving and complete a task quickly, you might say "build a fire under them." But there are several other phrases you can use to convey the same message. If you want to urge someone to act fast, you might say "light a fire under them" or "put a rocket under them." To encourage someone to work more efficiently, you can say "whip them into shape" or "crack the whip." And if you want to emphasize the importance of timely action, you could say "time is of the essence" or "don't dilly-dally." Regardless of the phrase, the objective is the same: motivate someone to get moving and accomplish their tasks quickly.
