frothing at the mouth
Literally 'foam at the corners of the mouth'; used to describe someone speaking with great excitement or anger, often in the phrase 口角泡を飛ばす.
He argued vehemently, frothing at the mouth.
Standard kanji spelling for this compound.
Mixed kanji-kana spelling; may be easier to read for learners.
Compound of 口角 (corners of the mouth) and 泡 (foam). The exact origin is uncertain, but it likely arose from the vivid image of someone speaking so passionately that foam gathers at the mouth.