Don't listen to that knuckle dragger.
knuckle dragger
idiomA large, strong, and rather dimwitted person.
Origin
disputed originAn allusion to the practice of some large primates of walking on all fours with their knuckles close to the ground.
The bouncer at the club acted like a total knuckle dragger when he refused to listen to my explanation.
Despite his imposing stature, he was no mere knuckle dragger, but a man of surprising intellect and quiet sensitivity.