An idiom meaning to be under strong pressure or urgency to act — to be pushed by a looming deadline and hurry to get something done.
締め切りが近づいて、ようやく尻に火がついた。
With the deadline approaching, I finally felt the pressure to get moving.
彼は試験前になると尻に火がついたように勉強する。
He studies as if his backside is on fire when exams are near.
プロジェクトの遅れでチーム全員の尻に火がついた。
The project's delay put everyone on the team under pressure.