屁をひって尻窄め
also: へをひってしりすぼめ
Meanings
1
closing the stable door after the horse has bolted; too little, too late
Proverb meaning it's pointless to take precautions after something has already gone wrong. The literal image is squeezing one's buttocks after farting.
Implementing safety measures after an accident is like shutting the stable door after the horse has bolted.
Studying after the test is over is too little, too late.