wacky (adj.)youdaoicibaDictYouDict[wacky 词源字典]
"crazy, eccentric," 1935, variant of whacky (n.) "fool," late 1800s British slang, probably ultimately from whack "a blow, stroke," from the notion of being whacked on the head one too many times.[wacky etymology, wacky origin, 英语词源]