also ratfink, 1963, teen slang, see rat (n.) + fink (n.). Popularized by, and perhaps coined by, U.S. custom car builder Ed "Big Daddy" Roth (1932-2001), who made a hot-rod comic character of it, supposedly to lampoon Mickey Mouse.
: the rat-fink Eastern press
A treacherous and disgusting person; bastard, shitheel: that rat-fink Danny's kid (1963+ Teenagers)
[perhaps originally fr labor-union use, since both terms mean ''scab'']