"an act of fraud, a swindle," 1969, from verbal phrase rip off "to steal or rob" (c.1967) in U.S. black slang, from rip, v. + off, adv.. Rip was prison slang for "to steal" since 1904, and was also used in this sense in 12c. Meaning "an exploitative imitation, a plagiarism" is from 1971. Related: Ripped-off.