when you are playing as the terrorists, and your team starts to lose, an arabic-accented voice will frantically yell out "WE HAVE LOST KHALID!!!!". When and if you start to win again, the same arabic-accented voice will say, in a much more calm and optimistic tone, "We have taken Khalid."
Simply put, when you have lost Khalid you cannot win the game, and if you have Khalid you cannot lose.
Why Khalid is so important to the COD4 terrorist team is unknown.
It is rumored that when Khalid isn't working as the unknown yet crucial member of the Call of Duty 4 terrorist team, he works at Durks, a popular middle eastern food stand in Manhattan, NY on the corner of 53rd street and 6th avenue.
Derived from the three letter Arabic root "kha lam dal".
Also commonly spelled as "Khaled" and mispronounced by anglophones as kaalid or kaleed.
from "We Takin' Over" by DJ Khaled
But it's really pronounced "Khalid"
Girl 2: I know right? He is the sexiest person ever
Khalid: Hi Girls
Girls: OH MY GOD ITS KHALID! WE LOVE YOU!!