  Recent observations of fast radio bursts (FRBs) indicate a perplexing,
inconsistent picture. We propose a unified scenario to interpret diverse FRBs
observed. A regular pulsar, otherwise unnoticeable at a cosmological distance,
may produce a bright FRB if its magnetosphere is suddenly "combed" by a nearby,
strong plasma stream towards the anti-stream direction. If the Earth is to the
night side of the stream, the combed magnetic sheath would sweep across the
direction of Earth and make a detectable FRB. The stream could be an AGN flare,
a GRB or supernova blastwave, a tidal disruption event, or even a stellar
flare. Since it is the energy {\em flux} received by the pulsar rather than the
luminosity of the stream origin that defines the properties of the FRB, this
model predicts a variety of counterparts of FRBs, including a possible
connection between FRB 150418 and an AGN flare, a possible connection between
FRB 131104 and a weak GRB, a steady radio nebula associated with the repeating
FRB 121102, and probably no bright counterparts for some FRBs.
