AKA manic-depressive disorder. This is when a person gets really sad for some time, crying for no reason, contemplating suiceide, avoiding people,
stuff like that. Then, one day it'll be over and they'll be all happy-go-crazy and stuff, buying a lot of stuff, turning promiscuous, and showing a general
ecstacy and lack of
foresight. This is a serious psychological disorder and should not be taken lightly. If you or a friend show signs of being bipolar seek help IMMEDIATELY! With proper support it is easy to treat.