Today in 1972, US Patent 3637117 A was issued, an invention of Mack S. Johnston, assigned to Republic Corp., for his “Keg Tapping Device.” Here’s the Abstract:

The device comprises a keg adapter mounted about a keg opening and a dispenser coupler releasably coupled to the keg adapter having gas inlet and beer dispensing outlet passages terminating in two side-by-side probes depending from the coupler. The liquid probe is movably mounted in the coupler and biased in one direction. An inverted J-shaped tube is carried by the coupler in communication with the liquid probe and displacement of the tube moves the liquid probe in the opposite direction to open the beer valve in the keg adapter. The gas passage is in communication with a hand operated portable plunger-type pump whereby gas is provided through the keg adapter into the keg.