  While gas accretion onto some massive black holes (MBHs) at the centers of
galaxies actively powers luminous emission, the vast majority of MBHs are
considered dormant. Occasionally, a star passing too near a MBH is torn apart
by gravitational forces, leading to a bright panchromatic tidal disruption
flare (TDF). While the high-energy transient Swift J164449.3+573451 ("Sw
1644+57") initially displayed none of the theoretically anticipated (nor
previously observed) TDF characteristics, we show that the observations (Levan
et al. 2011) suggest a sudden accretion event onto a central MBH of mass
~10^6-10^7 solar masses. We find evidence for a mildly relativistic outflow,
jet collimation, and a spectrum characterized by synchrotron and inverse
Compton processes; this leads to a natural analogy of Sw 1644+57 with a
smaller-scale blazar. The phenomenologically novel Sw 1644+57 thus connects the
study of TDFs and active galaxies, opening a new vista on disk-jet interactions
in BHs and magnetic field generation and transport in accretion systems.
