Sack is derived from the term "sack of shit". It describes someone who is unworthy of even being filled the feces that would reside within a "sack of shit". It is usually used to describe a person who is extremely lazy or is performing an extremely lazy act.
Friend #1: "Hey man can you shut the lights off?"

Friend #2: "Sorry bro. Busy."

Friend #1: "Dude you're right next to them. Just reach over and shut them off."

Friend #2: "Man that's too far away. I'm busy."

Friend #1: "Busy doing what? You've been playing League of Legends and eating toaster waffles on my couch for six hours."

Friend #2: "Exactly. I'm busy."

Friend #1: "You're a fucking sack."
by Kflop Fats January 25, 2013
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When someone slightly lies, but doesn't exaggerate the truth enough so that it is actually impressive. Most commonly used to increase ones self esteem, but not exaggerating so much that it is unbelievable.
CJ: You seem smart, what math course are you in?
Ian: Calculus AB
* actually in honors calculus *
Jason: First, why would lying about his math course make him look cooler? Second, why wouldn't he just say he was in Calculus BC if he wanted to look impressive?
CJ: I guess he was just sacking
by Bro Code Vocab July 1, 2015
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The male scrotum. Used as an exclamation for emphasis or to show dismay.
Asian: Hey dude you know we have a quiz in physics today?
White Boy: The sack!
by stuuuu October 6, 2006
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To like something.
To diggg it.
mainly used in northern virginia.
1) girl i sack your new top, it's so cute!
2) man that chick is sackin' me hardcore, she calls me everynight!
3) i know you sack her back!
by elz bellz November 4, 2007
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A natural phenomena when a man's testicals tighten and raise up, to allow access to the "taint". This could be caused by cold weather.
The water in the pool was so cold I had a sack-on.
by Mrpyz76 March 29, 2005
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Verb, mainly Scottish. The act of hitting a man in the testicles.
to sack

''Shut it you slag, or I will sack you.''
by diegothehumanrocket April 23, 2006
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Sack can be used in a number of ways:
1) to insult someone
2) to refer to balls
3) to describe a beating / misfortune
4) to subsitute the word 'shit'
1) dude, that guy is such a sack
2) lick my sack
3) that guy just got completely sacked by that crazy mofo
4) ohh sack that hurt
by ryan tanzi May 10, 2008
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