An earful is a long, usually angry telling-off where someone absolutely unloads on you. If you get an earful, you’ve been properly lectured and there’s no getting a word in edgeways. Can be from your mum, your boss, or some bloke in the queue who’s decided today is your trial. Classic British misery.
"Mum gave me a right earful for leaving three takeaway boxes under the bed. I tried to chat back and she went, Don’t you start, sunshine. I shut it."