Definition of rumble-de-thumps in US English:
rumble-de-thumps
noun
Scottish
A dish of mashed potato cooked with fat and often also cabbage, onion, etc.
Origin
Early 19th century. From rumble + an arbitrary element -de- + thump.
Pronunciation
rumble-de-thumps
/ˈrʌmb(ə)ldɪˌθʌmps/