from a creepypasta of the same name
Costume 1: Jeff in a light-gray jacket, black pants and black shoes.
Costume 2: Same attire as above except for the upper part, where he wears a light-blue tank top instead.
Jeff was just an humble preteen boy who, along with his family, moved to a rich, wealthy neighborhood. In his youth then, he had a fight with thrio of bullies who picked on him 2 times and on the second time, he killed three of them, after they dosed him with bleach and alcohol and set him on fire. This left Jeff, as he awakened, with pale, leathery skin, and red lips. He began to alter his appearance back at home by carving a permanent "smile" onto his cheeks and burning his eyelids. Afterwards, he killed his entire family. Now in his 20s after ten years, he has carried out his true passion, which consisted of a hundred manslaughters. Jeff saw a portal while the police were onto him and escape there to a realm called Outworld, which housed a death tournament called Mortal Kombat. Jeff, deciding he was tired of mostly killing helpless victims, wishes to fight there so he may take on a new and greater challenge, which is killing some more victims who can actually fend for themselves.
*Knife Throw: Jeff throws knives at his opponent; can be done repeatedly.
*Knife Boomerang: He throws a knife at his opponent two times before coming back to him, just like a boomerang.
*Knife Dancer: He twirls around with his knives erect slashing away at his opponent.
*Slash Dash: Jeff holds two knives and dashes through his opponent with a slash.
Jeff jump onto his opponent and uses two knives to stab his opponent in the eyes. Then he pulls his knives out and stabs the opponent in the cranium. Afterwards, he kicks his opponent to the ground.
*Go To Sleep!: Jeff headbutts his opponent onto the ground and then, as the camera then cuts to the opponent's first-person view, he ducks down to stare at him/her real close saying, "Shhh. Just go to sleep." and then he slowly raises his knife ad repeatedly stabs him/her, covering the screen with splattered blood as the opponent screams in agony.
*Skin 'Em Alive: Jeff turns his opponent to the back side and slashes him/her from behind upward. He then rips the back of the opponent open and takes out his/her bloody skeleton, as well as the inner organs that come along with the skeleton (since those organs are located inside the skeletal system anyways).
Baby Jeff jumps onto a pillow with a smiling face drawn on it and he repeatedly stabs it while he screams, "DIE DIE DIE DIE DIE!". 7 seconds later, he stops and then hides the knife behind his back, giving off a creepy-ass sheepish grin (it's creepy because of the scars on his cheeks that simulate a smile).
Jeff repeatedly stabs a screaming young woman off-screen for 4 seconds and then walks onto the battlefield, dragging his dead victim with him before throwing her away and telling her "Now go to sleep!". Then he looks at his opponent and gets ready.
Jeff throws a knife at the camera, cracking the screen as the knife pierces through it. Jeff laughs maniacally and rushes to pull the knife out of the camera, causing the screen to switch over to a TV error screen that contains a white rectangle at the center saying "GO TO SLEEP".
Jeff the Killer chose to take the challenge in fighting participants of the Mortal Kombat tournament so that he may take on strong individuals rather than just slaughtering the weak, most of which he killed throughout his life. Jeff killed not only Shao Kahn, but nearly anyone else he could take on in the tournament. His ruthlessness has impressed Kano, who figured that Jeff would make a great recruitment for the Black Dragon Clan. Kano brought Jeff into the Black Dragon stronghold and introduced him to his cyberneticist who gave Kano a cybernetic eye. Kano doctor has rebuilt Jeff from being the ordinary serial killer he once was to a much stronger, more faster, and far more powerful killing machine. Jeff has become a new subordinate of Kano's as well as a super-powered assassin for the Black Dragons. His first mission, to kill the former Black Dragon member, Kabal.