bite one's lip
- (idiomatic) To forcibly prevent oneself from speaking, especially in order to avoid saying something inappropriate or likely to cause a dispute.
1822, Sir Walter Scott, chapter 49, in Peveril of the Peak:
- Buckingham bit his lip, for he saw the introduction of Lady Derby was likely to confuse and embroil every preparation which he had arranged for his defence.
- 1922, F. Scott Fitzgerald, "May Day" in Tales of the Jazz Age:
- He broke off and bit his lip, feeling that he had better subdue the rising anger in his voice.