keg (n.) Look up keg at
1630s, earlier kag (mid-15c.), from a Scandinavian source such as Old Norse kaggi "keg, cask," of unknown origin. Cognate with Swedish kagge, Norwegian kagg. Specific sense of "small or half barrel of beer" is from 1945. U.S. student slang kegger "party featuring a keg of beer" attested by 1969.