Warren is a member of the Junior Campers. When Mrs. Krabappel announced a pop quiz, Warren reminded her that he had a patrol meeting, and she excused all Junior Campers from the quiz. This included Bart, as he had recently joined the Junior Campers (albeit while on a Squishee bender).
Warren's father is in prison. When Ned Flanders announced the father-son rafting trip at the Junior Campers patrol meeting, Warren looked downcast and started to cry. Flanders told Warren that a special celebrity dad had been arranged for him. Warren started to say that his older brother could come on the trip, but Flanders interrupted him: "I'm afraid that Ernest Borgnine has already been confirmed!"
When the rafts were separated, Warren was in the group of campers that stayed with Borgnine. They ended up being stalked and attacked by a mysterious person or creature while they were sheltering at an old abandoned summer camp. What happened to them after that isn't known.