What word or phrase does your mother always say?
late 13c., "from elsewhere, foreign, unknown, unfamiliar," from Old French estrange (French étrange) "foreign, alien," from Latin extraneus "foreign, external," from extra "outside of" (see extra). Sense of "queer, surprising" is attested from late 14c. Stranger, attested from late 14c., never picked up the secondary sense of the adjective. As a form of address to an unknown person, it is recorded from 1817, American English rural colloquial. Meaning "one who has stopped visiting" is recorded from 1520s.