WMG / The New Scooby-Doo and Scrappy-Doo Show

Scrappy is five years old in this series, in human-years.

In an episode, Shaggy tells Daphne, after encountering a 300 year old vampire, that he and Scooby are not interviewing anybody above the age of five. It's a funny joke, but it's also unusually specific. Scrappy, the child of the group seems a bit verbose to be only five years old (even if he's clearly meant to be The Baby of the Bunch) however, given that he's somewhat of an Innocent Prodigy, and his last Birthday Episode loosely implied him to be three (and aired two years earlier) Shaggy doesn't want to interview anybody anymore, but he knows that Scrappy, like any normal, mischievious youngster, is going to require some "interviewing" for proper care. So while it's also Shaggy being overly cautious and saying that he will only interview the five year old Scrappy from now on, for personal purposes, not editorial ones.