Dave makes a platter of lasagna for dinner. He places the last remaining piece in the back of the refrigerator. As Dave returned to his room he sees Garfield lying on the couch. Dave then states "Garfield I have lasagna in the refrigerator. You can have it if you clean the inside of the refrigerator. It really needs to be emptied out!" Immediately Garfield jumps up and cleans the refrigerator. Just as Garfield is about to eat the lasagna, Dave shouts "stop! I just  realized it is my friend Otis's birthday. Sorry, but I must give the last piece to him. Explain whether there is a contract that entitles Garfield to the lasagna.