zany

Short definition from Wiktionary

Adjective

1. 1
   Unusual and awkward in a funny, comical manner; outlandish; clownish.
2. 2
   Ludicrously or incongruously comical.

Noun

1. 1
   A fool or clown, especially one whose business on the stage is to imitate foolishly the actions of the principal clown.

Verb

1. 1
   To mimic foolishly.