Is it ensure, insure, or assure?
early 13c., geste, "narrative of exploits," from Old French geste "action, exploit," from Latin gesta "deeds," neuter plural of gestus, past participle of gerere "to carry, behave, act, perform" (see gest). Sense descended through "idle tale" (late 15c.) to "mocking speech, raillery" (1540s) to "joke" (1550s).
1520s, "to speak in a trifling manner;" 1550s, "to joke," from Middle English gesten "recite a tale" (late 14c.), from geste (see jest (n.)). Sense of "to speak in a trifling manner" is from 1520s. Related: Jested; jesting.