When you don't have the balls to shave your balls completely (it's risky...), resulting in a prickly sack almost like a cactus.
Francesca yanked down Billy's pants, cupped his ballsack, and immediately pulled away after realizing her hand was pricked by his sactus.
by jakedawg55 December 13, 2014
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A ball sack that has become prickly like a cactus because it hasn't been shaved for a few days.
Example 1 - "Dude, you have a sactus! When was the last time you shaved?"

Exaple 2 - "If you say that again, I'm going to have to slap you with my sactus!"
by Jujubear YT March 30, 2021
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When a male shaves his testicles and afterwards neglects to shave them for an extended amount of time resulting in hair growth that becomes prickly (much like a miniature bulbous cactus) and pokes the testicles or inner thighs constantly in a painful manner.
"Bruce thought he was going to have intercourse last weekend and shaved his testicles on Friday before going out for the evening. It's now Thursday and he told me that he hasn't shaved his nuts since last Friday, he must have a seriously irritated ball sactus."
by Joe CBone March 9, 2007
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