Not my truck!

Several weeks ago, Sullivan learned the word "mine." John thought it best that he wait a while to start saying that word so he would say to Sullivan, "It is not yours." Sullivan's favorite word is "truck" so of course he started saying "my truck" quite often. I guess John must have responded with, "It is not your truck." In the last 2 weeks, Sullivan's favorite phrase is "not my truck." Today, as we handed the saleslady a couple of videos to purchase, Sullivan said, "Not my truck." I think when he considers anything related to ownership, his reaction is "Not my truck." Poor little guy! Will he ever have anything that is his????