  Hydrodynamics and collision dominated transport are crucial to understand the
slow dynamics of many correlated quantum liquids. The ratio \eta/s of the shear
viscosity \eta to the entropy density s is uniquely suited to determine how
strongly the excitations in a quantum fluid interact. We determine \eta/s in
clean undoped graphene using a quantum kinetic theory. As a result of the
quantum criticality of this system the ratio is smaller than in many other
correlated quantum liquids and, interestingly, comes close to a lower bound
conjectured in the context of the quark gluon plasma. We discuss possible
consequences of the low viscosity, including pre-turbulent current flow.
