A lifenoob is an individual who lacks any life skills, streetsmarts or the ability to produce a decent comeback in a verbal fight..
Originating in halo 3 online, it originated when an american was unable to defend himself from some abuse i gave to him...
Cill: you're garbage.
Halo Player: no, you're garbage!
Cill: You are the worlds greatest lifenoob!!
one who is inexperienced in the ways of the world, failing on their first (or subsequent) attempts to do things due to lack of experience. Similar to a noob in that their actions often negatively affect other's perceptions of them.
That man just tried to change his tyre for the first time and managed to drop the car on his foot. I would call him a lifenoob.