To jerk only your sac when masturbating. Not the normal occassional tug on the sac, but pulling so hard that you nearly rip it off causing severe pain and swelling in the testicles. Usually done in conjunction with the bloody jack.
Your mom is hot, I think I'm going to sac jack to her and then beat the fuck out of her.
A type of manbag, but far more cool! Used by Jack Bauer of 24 to carry his awesome and unlimited arsenal of weapons to take on the terrorists that threaten the US
Jack: Dude, that manbag is so lame, you need to get yourself a Jack Sack
Nickname given to bales of marijuana thrown overboard or out of airplanes. Origin is reportedly from members of the US Coast Guard in the area of Southern Florida.
"Base we've got some square groupers floating outside of Miami harbor."