Fat Dog Mendoza is a really weird cartoon co-produced in Europe and the United States by TMO-Loonland, Sunbow Entertainment, Sony Wonder. It's the first ever Cartoon Network European co-production, and normally while most of them are hit-or-miss, this one isn't - in a way.
The series focuses on the titular Fat Dog, and his best friend Little Costumed Buddy, as they get into all sorts of strange and weird situations in the town of Neighbourhood X. It all starts with that guitar tune with all the things Fat Dog gets up to, then you know how weird this show gets.
Episodes range from Fat Dog being replaced with an identical dog, the Himalayan Mountains being moved into the backyard, to Neighborhood X being flooded by running bath water. They're weird, so weird, even more weirder, and weirdest of all. And I like it for that.
The voice acting is pretty interesting, featuring Canadian talent like Mark Acheson as Fat Dog himself in his voice acting debut.
The animation is weird as well, but I think it's fine enough for what it is.
In conclusion, if you remember Fat Dog from Cartoon Network back in the early 2000's, then you'll notice how weird it really is. It's not a cartoon for everyone, and I think it's best left that way.