quid pro quo 
/ˌkwɪdˌproʊˈkwoʊ/ noun
plural quid pro quos /ˌkwɪdˌproʊˈkwoʊ/ noun [count] : something that is given to you or done for you in return for something you have given to or done for someone else
▪ If he helps us, he'll expect a quid pro quo. [=he'll expect us to do something for him]
▪ If he helps us, he'll expect a quid pro quo. [=he'll expect us to do something for him]
