be like a red flag to a bull

be like a red flag to a bull

To be a willfully infuriating or aggravating provocation; to be something that incites great anger or annoyance. An allusion to matadors' practice of waving red flags at a bull during a bullfight, though the color of the flag actually makes no difference to the animal. John's gone to gloat about his success over his brother, which is like a red flag to a bull, if you ask me. You do realize that bringing your new girlfriend to your ex-wife's house is like a red flag to a bull, right?
See also: bull, flag, like, red
Farlex Dictionary of Idioms.
See also:
  • be like a red rag to a bull
  • a red flag to a bull
  • a red rag to a bull
  • close (one's) ears to (someone or something)
  • a security blanket
  • shut (one's) ears to (someone or something)
  • shut/close your ears to somebody/something
  • get (something) into (one's) thick head