From the article: What is 'negging'? 'Negging' is a slang term referring to subtle disparagement or passive-aggressive insults.
It's a shortening of the phrase 'negative comments.'
The term first appeared in the pick-up artist community, where it referred to demeaning a woman with backhanded compliments as a strategy for seducing her.
Once again, its not to demean women, its meant to display high dating value.
Weird.
Never heard of the word, but I wouldn’t do that anyway.