Answer: yabbadabbadoo

AnswerCrossword Clue
YABBADABBADOOHeard from 16A
YABBADABBADOOCartoon quitting-time shout
YABBADABBADOOFred Flintstone shout
YABBADABBADOOClassic cartoon shout
YABBADABBADOOStone Age shout
YABBADABBADOOCry of Fred Flintstone