Like everything else, He made it up to try and win the case, because he knew the petty evidence they had sucked. He knew the witnesses sucked. He knew the 'experts' sucked. He knew his whole case SUCKED!
It was so obvious during his cross exams and his closing statement. He had nowhere to go, to he just went in circles real fast and hoped no one on the jury would notice he wasn't getting anywhere.
And that's why he's now referred to as "Doosuk."