if a statement or an action is like a red rag to a bull, it makes someone very angry.
For Claire, the suggestion of a women-only committee was like a red rag to a bull.
be like a red rag 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 rags at a bull during a bullfight, though in fact the color of the rag makes no difference to the animal. John's gone to gloat about his success over his brother, which is like a red rag 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 rag to a bull, right?