When a person vigorously shakes a slurpee up and down in a masturbating motion in order to move the delicious slurpee product into a position that can be more easily sucked up by a straw. Usually this action is performed when there is mostly ice left and every time you suck the slurpee product does not fill in the air pocket created.
I really wanted the last bit of my slurpee, so I had to jack the slurp every few seconds to keep it coming up the straw.
by Udy October 16, 2008