Take the classic fable of the two sisters, quarrelling over a single orange. The sisters, who focus too much on cooperating with one another, cooperatively agree to cut the orange in half – a compromise agreement. One sister uses the juice and throws the rind away; the other sister uses the rind and throws the juice away, and then they realize – too late – that both sisters would have been far better off by giving all the juice to one sister and all the rind to the other sister. This is what is meant by “win-win” negotiation agreements, which are described as outcomes that improve upon mutual settlement by identifying ways that both parties receive better outcomes than by simply compromising on the issues at hand.
Source: Why negotiation is the most popular business school course by Leigh Thompson and Geoffrey J Leonardelli