A term that is most often used in the Halo franchise.
A deranker is someone who purposely loses or sabotages a game so that his or her rank
will go down. After they do it enough, they
will face opposition that can't compete with them and they'll win much more often. Thus making the deranker feel better about their own pathetic life.
Derankers often
will betray or teamkill to get the results they want. Luckily, in Halo 3 and beyond, Bungie made it more difficult for a deranker to prevail (no more negative suicide points, or placing the bomb outside of the
map).
When you're a lower level
player and there is a deranker on the opposite team, it is usually extremely obvious as they
will be considerbly better then everyone else in the game. You
will be able to tell that they shouldn't be in the same game as you. Derankers often taunt and make fun of their opponents after they
kill or beat them, acting as if they've earned some sort of bragging right- when in reality, they've earned nothing but to get labeled a noob.
Players also derank so that they can play with their higher level
friends and thus make matchmaking system bring in lower levels for a easier victory. Derankers are also called Delevelers. Deranking is frowned upon obviously, but it is seemingly not
cheating or breaking terms of service because Bungie does very little to punish these players.
