If you pay attention to what goes on around you
every day, you'll discover that stupidity is indeed
hard to hide. Because it's the lack of stopping
to think.
It can be a noun or verb. It means "spending (Or "to spend) time in a totally unproductive, stupid way by hitching a
ride on the back of an assumption."
Hermione lived her live as a total, complete dumfungle.
Or
He decided to dumfungle for the rest of the class period.