To keep pestering someone to do something, usually a boring job they’ve been dodging for ages. Nagging is the verbal equivalent of a dripping tap, constant little reminders until you crack or snap. Often said about partners, parents, or anyone who won’t let a tiny promise die in peace. Honestly, it’s oddly effective.
"Mum’s nagging me to sort the fence again. I said I’ll do it this weekend. She goes, You said that at Christmas, mate. Now I’m googling how to fix fences."