Despite his parents' warnings, Arthur has been letting Pal eat a lot of things he shouldn't --- everything from stale gummi worms from a Halloween possibly long past to a hot dog snatched directly from D.W.'s bun. Pal then starts looking ill and making a weird noise and ends up having to go to the vet and stay the night. Arthur is very worried, as Pal's never been away from him that long before. Worried about what's going to happen to Pal, he tries to shift the blame to D.W., convinced that she's done something after her statement that she would "teach that dog a lesson he'll never forget." (thetvdb.com)