doublecross

dupe, gull, gudgeon, gobemouche, cull, cully, victim, pigeon, April fool; jay, sucker; laughingstock; Cyclops, simple Simon, flat; greenhorn; fool; puppet, cat's paw.

be deceived, be the dupe of; fall into a trap; swallow the bait, nibble at the bait; bite, catch a Tartar.

credulous; mistaken (error).