have a run-in with (someone)
To have an unpleasant interaction with someone. I'm not going to her party because my ex-boyfriend will be there, and I don't want to have a run-in with him.
have a ˈrun-in with somebody
(informal) have an argument or disagreement with somebody: She had a run-in with her son’s teacher this morning. She doesn’t think he gives the children enough homework.