bon·kers (bŏng'kərz) adj. Informal
Crazy: "When word spread that free gas was to be found, the populace, as expected, went bonkers" (Washington Post).
bonkers "crazy," 1957, British slang, perhaps from earlier naval slang meaning "slightly drunk" (1948), from notion of a thump ("bonk") on the head.
www.urbandictionary.com/define.php?term=bonkersbonkers. Bananas, nuts, crazy, wild, ballistic, cuckoo! Any thesaurus will do. Quite commonly used word, not slang, used to affectionately describe a state of mind ...