be on about

be on about (something)

To be speak about something tediously and at great length. Primarily heard in UK. He just kept rambling about literary metaphors and imagery. I didn't know what he was on about! She's always on about some new show she has started watching.
See also: on

be on about

talk about tediously and at length. British informal
See also: on

be/go/keep ˈon about something

(informal, disapproving) keep talking about the same thing so that people become bored or annoyed: What’s she on about now?Don’t keep on about your terrible journey. It’s so boring.
See also: keep, on, something