A plunger, cup, plumber's friend or plumber's assistant is a tool used to clear drains and pipe jams. It consists of a rubber suction cup and a suction cup with a rod (shaft), usually made of wood or plastic. There are also different corrugated tubular designs, usually made of plastic.

For a common plunger, press the cup down against the drain, or press it firmly into the drain to force air in, or push it down until the rubber cup is flat and then pulled out, thus creating a vacuum to attract the material. The purpose is to dredge or eliminate the blockage caused by excessive substances in the drain pipe.