The
small, cylindrical
type of NOS/NO2/nitrous oxide dispenser. Usually made from 2 threaded sections of aluminium just long enough to accomodate an 8g nitrous oxide charger when screwed together. A spike in
one end of
one section pierces the cap of the charger when the halves are tightened, and
two small holes in the same end allow the
gas to escape into a
balloon stretched over the end. Available from headshops and presumably made exclusively for cracking NO2 chargers into balloons. So named because the user must
screw/jack the two threaded halves together in order to 'crack' or open the NO2 charger. Term is necessary in order to distinguish this style of dispenser from the larger cream whipper style sometimes referred to as a cracker. As the crackajack is a simple device with no intermediate chamber or valves between the charger and the balloon, NO2 decompression happens very rapidly, reducing the temperature of the crackajack significantly and invariably freezing the user's hands to the device.
Of note: while it is possible (though inadvisable) to
huff nitrous oxide directly from a cream-whipper style cracker, trying to do this with a crackajack will likely lead to excruciating injury due to the lack of any valve or trigger for pressure regulation.
Teenager 1: Hey man, pass the cracker
Teenager 2: Ah it's downstairs I think dude
Teenager 1: Nah nah the little one, the crackajack
Teenager 2: *passes crackajack to teenager 1*
Teenager 1: *freezes the shit out of their fingers then huffs some nitrous oxide*