Noun. A creepy meme (e.g. Jeff the Killer) that has been edited with a flashing effect and a loud noise similar to static. It is known as shitfuel because its sudden loud noise and flashing picture may cause an unsuspecting viewer to defecate in his or her pants, also known as "fueling shit," hence it is called shitfuel.
*link emailed to friend*
*friend goes to link, shits in pants because of flashing picture and loud, unexpected noise*
*person afterward* "That was some scary shitfuel."