Common name for "testicular akathisia"--also commonly known as "jimmy nuts": an uncontrolable urge to persistently shift, manipulate, or joggle one's testicles.
"Yo--he got he the Whack Sack serious. Dude plays with his nuts all day."
by Even Cleaveland December 31, 2006
1 more definition
A plastic bag used to carry drugs usually methamphetamine.
Billy lost his whacksack yesterday and he is still out there crawling around looking for it.
by Phil Mypipeup January 31, 2009