A serious mental disorder that the person who has can only do stuff if they yearn to do it. This disorder was first discovered in the anime, "Ultimate Otaku Teacher". Since then, many people have diagnosed themselves with it. Bill: Wanna go see that movie with me? Jessica: I can't, I have YD. Bill: You don't yearn to see that particular movie? Jessica: No, I don't yearn to see it with you.