だす

This grammar attaches to the stem form of a verb to express the moment something starts to happen, often with a sense of spontaneity, abruptness, or surprise. It highlights the transition from not doing something to doing it, as if the action begins suddenly. It can be used with many action verbs, and is common in narrative or descriptive speech when you want to emphasize the start of the action. The nuance is different from simply saying "to start doing"; だす conveys that the action begins unexpectedly or decisively. Note that the だす form is written in kana as だす even though many verbs are written with kanji + す (e.g., 笑い出す, 泣き出す). Typical usage is the stem (the verb’s continuative form) + だす, sometimes with the subject or context provided by surrounding sentences.