This article does not have any sources. (February 2013)
Leeroy Jenkins is the name of someone who was in the game World of Warcraft. He made a video which was put onto Youtube which some people think is very good. He has become known around the world and even has his own Achievement on World of Warcraft for pretending to be him in the video. His name is often spelt wrong as Leroy Jenkins who is a different person.
The video which made Leeroy so famous shown him and his friends, doing a friendly activity known as a Raid in World of Warcraft, but this activity is hard to do, so the leader of the group that Leeroy is with has to explain what to do. But Leeroy is not around for the explanation, and when he comes back, he ends up running in the area, shouting his own name as he goes, which begins the activity, and ruining the plan which his friends made. This causes everyone to panic, and no-one knows what to do, and so, everyone dies. Everyone blames Leeroy for this, and says "At least I got chicken."
Leeroy has become very well known and his name is now used by people to show that they are running in but have no idea what to do. These people should be avoided, as they may cause you to die as well, as the video shows. Because of this, people now consider the video to be a Lesson.