rave

rave vi.  [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 evangelize.  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.