[WPI] 1. To persist in discussing a specific subject.
2. To speak authoritatively on a subject about which one knows very little.
3. To complain to a person who is not in a position to correct the difficulty.
4. To purposely annoy another person verbally.
5. To evangelise. See flame.
6. Also used to describe a less negative form of blather, such as friendly bullshitting. "Rave" differs slightly from flame in that "rave" implies that it is the persistence or obliviousness of the person speaking that is annoying, while flame implies somewhat more strongly that the tone or content is offensive as well.