A member/player of your team who is almost bound to failing badly in most cases and cause more damage to their own team than to the enemy.

They are a liability and an unfavourable member of you're team.

Team Killer/Failure- can be used as an adjective Abu Hajaarer
Failing Hard/Team Killing- can be used as a verb Abu Hajaaring
(Origin of word began in the Youtube comment section of a video and was used as a gag by ISIS members to identify and describe noobs and team killers)
"Before this battle in ISIS HQ

Fighter " sir what's are plan of attack to push back the infidels?"

Commander "the plan is we will launch a frontal assault in armored vehicles over completely flat terrain in broad daylight toward a fortified hilltop position with no cover or means of retreat or resupply "

Fighter "that sound like a fucking stupid idea, and are armored vehicles are a APC and and a some trucks with some metals sheets bolted on!"

Commander "That's not my problem, oh and Abu Hajarr is going with you."

Fighter "we're fucked."

or
"When I play multiplayer games, 95% of my teammates are Abu Hajaar. "

(see video and comments for sources of examples)

add "/watch?v=aM3ElTvF52I " to the youtube url for video
by Eristed May 1, 2016
Get the Abu Hajaar mug.