Today in 1998, US Patent 5735425 A was issued, an invention of Leigh P. Beadle, for his “Reusable Beer Keg Plug.” Here’s the Abstract:

An improved reusable beer keg plug replaces the conventional wooden bung and is formed of an elastomeric material as a tapered, expandable plug suited to being snugly fitted within a conventional beer keg sidewall tapered hole and thereafter expanded by an adjustable tightening device forming part of the plug.