I wish to know meaning of phrase / expression wacky duck

I am writing a story at the moment about one villain from a horror movie and I often need rhymes. English is not my mother tongue. I read on Urban Dictionary that "wacky duck" means a hit to a man’s genitals. There is one example. I gave him a wacky duck after he stepped on my foot.

Here is a source

https://www.urbandictionary.com/define.php?term=wacky%20duck

I wish to use wacky duck in my story but I can’t use it before I am sure that it means as I read in Urban Dictionary. I wish to know is this expression correct, does anyone use it? Some area or city? Maybe it is new expression that not many people know? I asked few people but nobody ever heard about this expression :(. I hope somebody will know the answer. Thank you in advance :o).