Knuckle Dragger Meaning

(idiomatic, often derogatory) A large, strong, and rather dimwitted person.

Example: 2008, Pat Hickey, "Prepare the Pulitzer," Chicago Daily Observer, 21 Dec. (retrieved 5 Jan. 2009):
  Mickey was wide receiver on the St. Rita Football Team in 2007—a big strapping, robust south side knuckle dragger and chick magnet.