NeedABrain is a mispelling for "Need a brain?" which in turn is a geekish slang for one's offering him/herself to do another's homework. Geeks can say "need a brain?" for sex, money or just to avoid being beaten.
The Uncyclopedia user that identifies him or herself as NeedABrain and writes in third person was already known by this alias in his or her previous incarnation as a human being. Now he or she is reduced to the state of brain-in-the-vat, but he or she is happy and don't be a prejudiced bigot. It's okay to be gray, you know? Brains-in-the-vats still have feelings, can be very cuddly, live just to make you smile and don't have to deal with foul body odours.
There was a time when the entity now known as NeedABrain, was it a boy or a girl, was a human being like you and Brian Molko. How he or she turned in his or her current form is a long history, but maybe we can sun it up to this: do you know transcendental meditation? That stuff of taking your mind out of your body? Well... it works! (His or her eternal gratitude to the paramedics that were quick with the mayonaise jar).
