I think you're confusing negging with teasing and having fun. Like giving eachother a hard time in a lockerroom after training, it's good for your value among your friends to be 'well spoken'

but that's something different then negging. Friends are your friends, they are your social proof, you hang out with them and you help eachother out. They hang out with you, because you're a cool guy and you respect eachother. Don't neg your friends to demonstrate a higher value to strangers, because if you do, you'll give the impression you're a show off. I think if you want to demonstrate a higher value, you're better of by having a lot of fun with them and by that you're demonstrating that you're a cool guy.
Mystery about a neg: The girl is failing to meet your high expectations. It's not an insult, just a judgement call on your part. You're not even trying to make her feel bad. It's the same as if you pulled out a tissue and blew your nose. There's nothing insulting about it. You haven't explicitly rejected her. But at the same time, she will sincerely believe that you aren't trying to impress her. This creates curiosity and makes you a challenge.
Neg's are created to disarm a HB's bitchshield. The hotter the girl the more you neg. Until you 'created' a mutual respect between you two.
There is already a mutual respect between you and your friends..