When grabbed, it summons a horde of Slender Zombies. The Cursed AK-74 is a red reskin of the normal AK-74, but does more damage (capable of taking down normal zombies in one shot) and makes a different firing noise, which is pretty close to thunder.
The Cursed AK is an AK that can be found in the Tall Grass on an Altar. The easiest way to locate the Cursed AK is to listen to the ominous music that the Altar emanates and to look for the patch of dirt with no tall grass surrounding the alter.
Also, Cursed AK is known to drop from Giant Zombies.