Today in 1978, US Patent 4089444 A was issued, an invention of Ronald E. Shea, for his “Tapping Apparatus For Golden Gate Type Beer Keg Openings.” Here’s the Abstract:

A beer keg tapping apparatus for golden gate type openings comprising a keg unit consisting of a stepped annular member in which valve controlled gas and liquid passages are disposed and which is adapted for insertion into the beer keg through the golden gate opening, and a stepped annular coupling member which is adapted for slidable disposal over the keg unit and includes first and second external threaded portions for engagement with the keg opening for securing the keg unit therein and with a tavern unit for tapping beer from the keg, respectively.