The story
Probably an alteration or variant of bumble (verb), perhaps influenced semantically by association with amble (verb). This term is originally nautical and military in usage, and is previously used outside the current meaning of traveling on foot.
First known use, by meaning
- from 1980s A walk or journey with no particular haste.
- from 1980s To walk or travel with no particular haste.
Etymology from Wiktionary, CC BY-SA 4.0.