From Homestar Runner Wiki
He has a possibly major, but mostly unseen, role in The Li'l Brudder Show, as it is sometimes called the "Li'l Brudder and Maybe Tendafoot, Too Show". In the show, he is seen hanging out with three other deformed animals, namely Li'l Brudder, a parrot and a possum, forming a group known as The Dregs. He seems to think that Li'l Brudder's name is actually "Piddles."
Even though Strong Bad's drawing calls this character "Tendafoot", The Brothers Chaps always pronounce it "Tenderfoot".