1. Someone who muddles their way through something in an inept, haphazard manner; a blundering, incompetent fool. With a stumble-bumble like him running the company, it's hard to believe we haven't gone bankrupt yet. She may have been an amazing businesswoman, but she is has been absolute stumble-bumble as our governor.
2. dated slang Any powerful, addictive narcotic, especially a barbiturate. Typically used in plural constructions. The officer could tell the two suspects were high off their gourds on stumble-bumbles.