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.