trail (one's) coat
To incite an argument. If one literally trails one's coat, a passerby could easily step on it, thus creating a tense situation. With a comment like that, she is clearly trailing her coat, and I refuse to take the bait.
trail (or drag) your coat
deliberately provoke a quarrel or fight. If you trail your coat behind you someone is likely to step on it, either intentionally or unintentionally, so enabling you to pick a fight. This behaviour was traditionally associated with Irishmen at Donnybrook Fair, an annual fair once held in what is now a suburb of Dublin. Charlotte M. Yonge , in the novel Womankind ( 1877 ), alludes to this association: ‘Party spirit is equally ready to give offence and to watch for it. It will trail its coat like the Irishman in the fair.’
1980 James Ditton Copley's Hunch I was trailing my coat…Trying to get the Luftwaffe to come up and fight.