"Stir up" is a phrase that is commonly used to describe the action of causing something to happen or creating a commotion. However, there are several other synonyms that can be used to express this idea. One option may be to use the phrase "rile up," which means to provoke a strong emotional response in someone. Another synonym may be "agitate," which can describe the act of stirring up feelings or creating unrest. "Instigate," "generate," and "provoke" are also words that can be used to describe the act of stirring up something. By using these varied synonyms, writers are able to add depth and variety to their writing to better convey their ideas.