Top definition
A male version of the infamous camel toe, esp. when flaccid.
"Holy cow! That is the biggest slack knuckle I've ever seen!"

"That guys pants are so tight his slack knuckle is poking out like crazy."
by Jadder Obbins July 07, 2008
Get a slack knuckle mug for your cat Zora.
Aug 9 Word of the Day
Large, beautiful breasts that are keep well consealed and initially appear to be much smaller and less impressive than they actually are until unleashed.
I think Alicia may have some real sleepers.
by KABT October 26, 2007
Get a sleepers mug for your mom Jovana.