1. A short response used as a secretive way to let out anger towards a person you dislike in conversation, or something they said that you dislike or don't agree with.
2. Also used in situations as a response to a person asking you to do something you don't want to do.
Mother: Hey honey, can you take out the trash for me, please?
Fucked Up Beyond All Hope
I'm fubah because my marks are a shit