Quid Pro Quo: ("what for what" in Latin) most often means a more-or-less equal exchange or substitution of goods or services.
Spinning Quid Pro Quo: The ability of the giver to make the receiver of the exchange believe that not only was it a good idea, but he/she is doing a favor and the services they are giving are worthy of not only the first exchange, but for all exchanges in the future. But this is OK, because the receiver likes/loves the giver so very much, they are willing to do what it takes to please them. This state of being is often shared between users and people pleasers. It benefits both very well. For an alternate definition, see any episode of Entourage.