Disclosed are an apparatus and related methods for quickly deactivating or otherwise plugging a sprinkler, wherein the deactivated sprinkler may automatically reactivate in view of an unexpected fire. Generally, the disclosed apparatus comprises: a forked clamping arm and a jaw arm with a stopper plug, wherein the forked clamping arm is positioned around a body of a fire-sprinkler and the plug is squeezed against an outlet of a fire-sprinkler via locking plier action between the clamping arm member and the jaw arm member. Suitably, a water tight seal is created by the plug over the outlet. Preferably, the plug of the apparatus may be configured to melt whenever ambient temperatures surrounding the sprinkler reach a threshold level so that the sprinkler may reactivate in view of an unexpected fire in its proximity.