dupe (n.) Look up dupe at Dictionary.com
1680s, from French dupe "deceived person," from Middle French duppe (early 15c.), thieves' jargon, perhaps from phrase de huppe "of the hoopoe," an extravagantly crested and reputedly stupid bird.
dupe (v.) Look up dupe at Dictionary.com
1704, from dupe (n.). Related: Duped; duping.