Relates to online FPS games. A person who is easy to kill.
This person will help you to level up. He can be found walking slowly around the map you are playing. Instead of hugging the walls or making good use of the cover he seems to be wandering around aimlessly.
On the negative side this person has no idea of tactics so his random actions may score him at least one kill.
An 'easymeat' is said to be a person with little education and no life achievement to speak of. Generallyunemployed and happy to have others pay their way in life.