Definitions of rattling:

• noun:   a rapid series of short loud sounds (as might be heard with a stethoscope in some types of respiratory disorders)
• adjective:   quick and energetic

  Example: "Traveling at a rattling rate"

• adverb:   used as intensifiers; `real' is sometimes used informally for `really'; `rattling' is informal

  Example: "A rattling good yarn"