A hazing ritual or punishment in which an unlucky fellow is strapped to a pole or board, and with the help of many assistants is moved back and forth under an obese unwashed man's undercarriage, from the top of the crack to the back of the sack, in a wiping or scrubbing motion until dead or unconscious.
"Greg informed us that Revenge of the Sith is his least favorite Star Wars film, so I petition that his punishment will be a GrundleButter Keelhaul."
A punishment in which an unlucky fellow is strapped to a pole or board and then held up by several men and swiped back and forth under an unwashed obese man's undercarriage, from the top of the crack to the back of the sack, marinating in the unholy 'butter' found therein.
"Jonsaid he doesn't like Star Wars, so he has been sentenced to a GrundleButter Keelhaul"