The antonyms for the term 'fat' are thin, skinny, slender, and lean. The antonyms for 'dumb' include intelligent, clever, bright, and smart. Lastly, the antonyms for 'happy' are sad, gloomy, depressed, and miserable. These antonyms provide a contrast to the term 'fat dumb happy.' For instance, while being fat, dumb, and happy may denote positivity, being skinny or thin, clever, and sad or depressed are the exact opposite. Overall, knowing antonyms for different words can help you understand language better by adding contrast, especially in situations where the meaning might change depending on the context.