Definition 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

"Traveling at a rattling rate."

adjective: extraordinarily good or great; used especially as intensifiers

"Had a rattling conversation about politics."

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

"A rattling good yarn."