zany

Concise Oxford English Dictionary © 2008 Oxford University Press:
zany/ˈzeɪni/

▶adjective (zanier, zaniest) amusingly unconventional and idiosyncratic. ▶noun

• 1 a zany person.

• 2 historical a comic performer partnering a clown, whom he imitated in an amusing way.

– derivatives
zanily adverb,
zaniness noun.

– origin C16: from Fr. zani or Ital. zan(n)i, Venetian form of Gianni, Giovanni ‘John’, stock name of the servants acting as clowns in the commedia dell'arte.