Idiom used here and there by Some People
ˈhɑːpɪŋ ɒn • To moan about something, usually something unimportant. It also infers that the person complaining is being slightly annoying. It can also mean to talk excessively about something in a persistent and annoying way.
"I wish you'd stop harping on about the football, you've done nothing but since yesterday"
Added November 2020 by blubs