屁をひって尻窄め
1
there is no use shutting the stable door after the horse has bolted;squeezing your buttocks after you have farted
Other forms
屁をひって尻つぼめ 【へをひってしりつぼめ】 · 屁をひって尻すぼめ 【へをひってしりつぼめ】