The term yinyang is derived from the Chinese philosophy of yin and yang and describes a particular type of verbal/written exchange between two people, someone can be yinyanged when after coming out with a witty testy or otherwise flirtatious comment or friendly put down the target instantly redeems themselves by yinyanging back with an equally witty response flowing with rather than against the initial comment given.
Woman: "Dont say rofl, its not cool :)"
Man: "na not cool at all but since you have enough cool for the both of us I decided I'd be the hot one for the sake of equilibrium."
Man: "shortie just got yinyanged, lets see you step up now.."