Brown stuff can refer to a variety of things, from food to waste, and it can be difficult to find alternatives when describing these items. Some synonyms for brown stuff can include chocolate, dirt, mud, poop, or even gravy. If you're referring to brown food, you may consider using descriptions such as nutty, earthy, or caramelized. For waste or excrement, you could use terms like feces, dung, or excreta. Ultimately, the word you choose will depend on the context and tone of your writing, but it's always helpful to have a few synonyms on hand to make your language more varied and interesting.