Head smashing was also present enough in episode 5x09 to give us reason to believe Negan is around. When Noah found his old house, he found his mother with her head smashed in the living room. Very similar to what Negan did to Glenn.
A trade-off is a situation where you make a compromise between two things, or where you exchange all or part of one thing for another. ...the trade-off between inflation and unemployment. American English: trade-off
A car's trade-in value is the amount of money an auto dealer is willing to take off the purchase price of a new or used car in trade for your existing car. The trade-in amount is based on a number of factors, including the make and model of the car, its age, and its condition at the time of trade.