"Matt's Lunch Box" is a short story in More & More Tales to Give You Goosebumps.
On the first day of spring, Matt Green comes home from school. Matt was going up stairs, but as he passed the kitchen, he noticed his mom was in it. She asks Matt to have a snack, but he refuses. Matt explains that his mom is always trying to force him eat more, because she thinks he's too skinny.
He tells his mom that he forgot his lunch box in the bus, so she has to buy a new one. Later that day, Matt's mom buys a red plastic rectangle container. It had a comic of three monsters chasing a boy. Matt took the lunch box and went up to his room, then he slammed himself on the bed. He was staring at the picture in his lunch box when he noticed the monsters were flying out in the same lunch box in the picture while chasing the boy across the kitchen.
He cracks it open and hears voices inside that tell Matt that they're hungry. Startled, he closes the box, but, later that night, he hears noises coming from the lunch box. The voices beg Matt to let them out.
The noises grow harder and, suddenly, the monsters zoomed out towards Matt, saying that they want food. Matt tells them that he doesn't have any food. One of the monsters bites Matt and says that they're going to eat him. Matt gives them all the food he has, and the monsters eat it.
At breakfast, the monsters eat Matt's food, and, at school, Matt notices his lunch box is empty. The monsters keep eating Matt's food for three days, causing him to get very weak.
Matt remembers the monsters said that "whoever owns the lunch box also owns the monsters". Matt then has an idea. He sees a yard sale selling everything for 50 cents, and Matt puts his lunch box on one of the tables. A few minutes later, a lady buys the box. Matt goes home and starts eating as much food as he can.
Later at dinner, the door bell rings. It's Matt's uncle Murray, who says he brought something to Matt. He reaches into a plastic bag and grabbed a red thermos. His mom proclaims that is has the same design as his lunch box. Matt stares in horror as he sees the little monster wink at him and whispers, "Boy am I thirsty!"