Slang Eccentric or irrational: a wacky person. (adjective)
Slang Crazy; silly: a wacky outfit. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "wacky" in a sentence
"Wild incomptence can also work ... or just plain wacky/random things (see: nobody expects the spanish inquisition!) # Wingson 16 Apr 2009 at 7: 57 pm"
"Dressed in wacky clothes, says funny stuff like, “I like pizza.” and “I got a wallet.”"
"Kim Possible, Pinkie and the Brain, Invader Zim and many other comedies threw in wacky, wacky plots from time to time."