A ning-nong, frequently abbreviated to nong, is someone who has
done something
stupid or clumsy and has caused a nuisance to others. Although it is can be an
insult, it is often used affectionately, especially by Australians.
"Ah Charlie, you're such a
ning-nong!" (in reply to a deliberately
weak joke.)
Why did you go and invite that ning-nong to our barbecue? He's embarrassing all our guests!
"Stop being such a ning-nong, will you? You're upsetting your sister!