[from the name of a TV clown even more losing than Ronald McDonald]
adj. Resembling or having the quality of a bozo; that is, clownish, ludicrously wrong, unintentionally humorous.
Compare wonky, demented.
Note that the noun 'bozo' occurs in slang, but the mainstream adjectival form would be 'bozo-like' or (in New England) 'bozoish'.