Today in 1937, US Patent 2083281 A was issued, an invention of Fred M. Spayd, for his “Beer Tap Fitting.” There’s no Abstract, though it’s described this way in the application:

This invention relates to liquid dispensing apparatus and more particularly to beer dispensers and cleaning apparatus therefor.

One object of the invention is the provision of a beer keg or the like having a thing through which the draft tube can be inserted and having a bayonet connection with the keg bung, the fitting having a self-closing valve adapted to be opened and to be held open by the draft tube, but normally closed when the draft tube is withdrawn so that the pressure within the keg may be maintained.

Another object of the invention is the provision of a self-closing valve fitting adapted to be readily attached to and disconnected from a barrel bung, and having attaching means at its opposite ends which are complementary to one another so that the fitting is adapted for use with standard connections.