"Jagoff" (sometimes "
jag-off") seems to have originated in Pittsburgh but is also recognized in the Midwest as slang for an inept, feckless, contemptible, or generally worthless person, a
loser, a "schlemiel."
The term is
almost certainly derived from the verb "jack off" (through noun "jack-off") as in "
masturbate," but somewhat like the British use of "wanker," it is usually not a direct comment on self-pleasuring, but more of a general term of contempt or deliberate abuse. Like "wanker," "jagoff" is somewhat vulgar and not to be used lightly, and avoided in cultivated speech, but is recognized by all in the regions in which it has currency.
.
The book KILLER CLOWN relates that John
Wayne Gacy became especially flustered or
angry when called a "jagoff." So the
police deliberately used that term to throw him off-balance during interrogation.
.