rubby-dubby
/ˈrʌbɪˌdʌbi/British Angling
noun
Minced fish such as pilchards, mackerel, etc., placed in a net bag and used as a lure for sharks and other large fish.
Origin
1950s. Origin uncertain. Perhaps a reduplication of dub, perhaps suggested by rub-a-dub, rub-a-dub-dub, etc.