A person, dog, or cat, who is overweight due to overeating or lack of exercise. Generally, the extra weight will be centered around the middle (or gut), thus creating a rotund appearance.
For humans: I can't find a dress shirt that doesn't look like a tent. It seems like all these dress shirts are really made for Fatty McFattersteins.

For dogs/cats: My cat lives for breakfast and dinner and she has an extra pouch hanging down. What a little Fatty McFatterstein.

by Sara Alize Cross January 8, 2009
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