Walter grew up with his brother Gary. While they get along great they are quite different. Walter looks like a muppet, while Gary looks like a man. Walter also has a feeling he doesn't really belong, and is a big fan of the muppets that he knows from TV. Growing up means becoming who you want to be, so eventually Walter decides that he is a very manly muppet, while Gary decides that he is a muppet of a man. Growing up also means that Walter and Gary besides being and staying loving brothers, each have to find a life of their own. Walter finds out he is very good at whistling, and finds a place among the other muppets.