A proper noun phrase formed by the compound nouns “machine gun” and the personal name “Kelly.” In everyday usage, it refers to a specific rapper/act, often as a stage name, and is pronounced with the rhythm and stress patterns of multi-word names in English. It is not an ordinary adverb despite your prompt’s part of speech; as a name, its pronunciation follows channelled noun-name conventions rather than regular adverb morphology.
Full pronunciation guide
