Summer Work

My oldest son is home from college for the summer. Every year he works at Great Adventure and saves his money to live on for the upcoming school year. Last year his savings lasted till December, at which time, I started sending him money at school to live on. I'm a single mother, with three children. I make a very modest salary and get very little child support. This summer I let him bring home his boyfriend for the summer. He has NOT accepted his job back at Great Adventure [GA]. He says he is looking for an internship. I want him to work at GA until he finds something. He & his bf are up all night watching TV, playing video games, eating lots of food. They wake up at 3pm. This is the first time I have EVER had a problem with him. He refuses to listen to me. HELP. Anyone out there with an answer. I need a good dialogue I can start with him to get him to act responsibly. I can't afford the food and am scared to death of the cost of this to me. All answers are welcomed.