I only remember seeing one episode in my life... an English dub of "Invasion of the Pig Clones"... but it stuck with me my whole life as one of the funniest and quirkiest things I ever seen, almost rivaling Animaniacs in the left-of-left-field department of comedy. In addition to that, it is almost relatable, as I grew up with a wild imagination and often wished one of my imaginary friends-- much like Sunny Pig for the lead boy-- somehow became real and made anything I can think up become real, almost believing the wild adventure would be worth the set-backs.
As a person with Autism, I can relate to the struggle to fit in when something about me seems "weird", but any kid, much like Spencer, would be caught between wanting to be normal enough to fit in and craving a life spontaneous and crazy enough to stand out and be worth talking about later on despite the odd looks one would get, and it is clear that he-- though his friendship with his "pet" pig-- channels the balance between the two extremes in a healthy manner, unlike a certain classmate of his, who thinks the key to greatness is to build a reputation as a weirdo on purpose while he's still young and doing so on unnerving, inhuman levels. Eccentricity and the creative thought process that comes with it isn't something that should be forced, but used in a way that allows a gifted child to express oneself freely and then reel back into the real world when the adventure is over before the cycle somehow happens again. THAT is the "Sunny" side of childhood that the show manages to capture.