Cactus plugging is the practice of vandalizing or destroying a cactus, usually a saguaro, for fun. Typically the cactus is cut open, drained, then packed with explosives and ignited. In another variation, the vandal simply shoots bullets into the cactus body until portions fall off or the entire cactus falls over.
In one notorious incident in 1982, one David Grundman was killed when an arm of the saguaro he was "plugging" fell on him. A song by the Austin Lounge Lizards (co-written by Ann Clardy) poked fun at Grundman's stupidity.
The act of cactus plugging, if performed on a saguaro, is illegal. In any case, it is a particularly destructive form of vandalism, as saguaros require over a hundred years to reach a substantial height.