There are several synonyms for the phrase "write erratically" that you can use to describe someone's writing style. Some of them include using words like "scribble," "scrawl," or "dart," which suggests rapid, uneven movements. Alternatively, you can use terms like "jot," "doodle," or "scratch," which imply that the writer is aimlessly putting pen to paper without much thought. If you want to convey a sense of confusion or disorder in the writing, consider using terms like "jumble," "muddle," or "clutter," which indicate a lack of organization or structure in the text. Whatever word or phrase you choose, make sure it accurately describes the writing style you are trying to describe.