harp on about something
From Longman Dictionary of Contemporary Englishharp on about something British English, harp on something American English phrasal verb informalTALK TO somebodyto talk about something continuously, especially in a way that is annoying or boring My grandfather harps on about the war all the time. → harp→ See Verb tableExamples from the Corpusharp on about • But the Tories would be unwise to harp on about Mr Kinnock's.