1. A moron from a low social caste. Picture someone with a sunken forehead, low hairline, and prominent chin.
2. A guy who goes to the gym seven days a week, probably does steroids, and has a body that looks like a comic-book character. He might be 5'4" but his arms and shoulders are so overbuilt that he looks ridiculous.
If you go to Gold's Gym in the afternoon there are nothing but mouth-breathers.