Occurs over the course of time when an attempt to be intellectual or keep a train of thought is made.This is then followed by a sputtering and finally an epic fail on the part of the absent minded individual who manages to make themselves look like foolish idiot.
Girl: I don't know what's wrong with him. He can't keep up a conversation, always wanders off to an unrelated topic.
Friend: Does it happen often?
Girl: Yes!
Friend: He's probably suffering from Blue Brains.
Girl: But why? What would have caused it?
Friend: Most likely he's distracted by his Blue Balls.