Disagree makes your character disagree to someone. If the command is directed to a certain person, all people in the room will see you disagree to this person, and the person in question will see you disagree to him.
EXAMPLES
"disagree"You: You disagree. Anybody: Hotblack disagrees."disagree to Marvin"You: You disagree to Marvin. Marvin: Hotblack disagrees to you. Anybody: Hotblack disagrees to Marvin.