expression, godan verb (-ru)
dig one's own grave; bring ruin upon oneself
Idiomatic expression meaning to cause one's own downfall through foolish actions or words.
あんな発言をしたら、墓穴を掘ることになるよ。
If you make a remark like that, you'll be digging your own grave.
彼
He dug his own grave by revealing the secret.