Traditionally meaning "total
idiot", duffer is a mashup which translates to "dumb
fucker." Generally viewed as an appropriate term for elderly
people who make absolutely zero sense to a rational person attempting to understand their reasoning for doing what they do.
"Why is there a brake
drum in the
dish drainer?" "I don't know. Ask Duffer. It's his house"
Upon seeing shredded bits of garden hose scattered across the
yard, it's safe to assume duffer ran another one over with the lawn mower.