We demonstrate that a system formed by two coupled graphene sheets with a drift current may enable pumping graphene plasmons, leading to spasing in the mid-infrared range. This regime relies on exponentially growing wave instabilities that are triggered by drifting electrons streaming through one of the graphene sheets. The nanoscopic characteristic dimensions, together with the wideband tunability, make the proposed structure very attractive to be used as on-chip light source in nanophotonic circuitry.