From Homestar Runner Wiki
Strong Bad envisioned Da Huuuuuudge in animal, after deciding that he'd been over-thinking ideas for his own made-up animal. He tried to create a name first, and let the name dictate what the animal will look like. As a result, Da Huuuuuudge looks like a big yellow bubbling blob with a Strong Bad face on it. It also sports some The Cheat-like spots. Apparently only one of the six consecutive U's in the creature's name needs to be pronounced.
He is the only rejected imaginary animal to make a reappearance in alternate universe. He is apparently able to support Strong Bad's weight, and, somewhat unexpectedly, has a very high singing voice.
Da Huuuuuudge lives in a fenced off area, which is apparently located in a zoo, as it features a sign warning visitors not to feed Da Huuuuuudge (emphasized by an appeal to "the love of Pete") and was visited by Marzipan. There is a slowly expanding dark stain spreading through the grass beneath Da Huuuuuudge, perhaps indicating that he secretes some kind of oily substance. It is not known whether the enclosure is actually located in Free Country, USA.