Like incestuous, but with your friends. A group of friends that's oddly, freakishly close with each other. Hold hands, occasionally kiss, share toothbrushes. Sometimes significant others of the friends get jealous of how touchy feely they are.
Those girls over there are so friendcestuous. It's kinda hot, actually. They keep cuddling and licking each other.
Friendcestuous - meaning to have a group of friends that will date each other , break up and date each other's exs in the friend group and not be bothered by it.
I don't go near molly because her friend group is Friendcestuous and I don't want too much weirdness and dramatic for my taste.