情绪怪病

'Mood Disorder.' Using this nickname, a person may suggest he suffers from mental illness like Bipolar Affective Disorder which is also referred to as Manic-depressive Disorder. But it may as well refer to the speaker’s moodiness and changesable emotion. He has complicated and variable emotions every now and then, but sometimes he enjoys such mood swing. It implies this person may be a little bit hard to deal with.