(n.) a term used to describe a gentile, or non-Jew, who engages in intercourse with a Jew one or more times, thereby, becoming somewhat of an honorary Jew of sorts.
A phrase used to express the truthfulness of a statement, much like scout's honor. Considered impolite or not politically correct because "injun" is a slang term for an Native American Indian. This phrase has not been in common use for decades.