zany (n.)
comic performer, 1580s, from French zani, from Italian zani, zanni "a zany, clown," originally Zanni, Venetian dialect variant of Gianni, pet form of Giovanni "John;" thus equivalent to English Jack. A stock character in old comedies, he aped the principal actors.
zany (adj.)
1610s, from zany (n.). Related: Zanily; zaniness.