An operator of a privately or commercially owned automobile (typically a Toyota Prius) who has gone full-retard and operates said automobile at a speed well under the designated speed limit in the left-hand lane of a multi-lane roadway when other roadway lanes are clear and free of traffic -or- other roadway lanes are loosely occupied by other motorists traversing at a similar speed.
I swear to God, if this left lane lurker doesn't merge over I'm going to fucking ram his Prius off I-40.