I assume it's an example of the rapier-like wit of another knuckle-dragger.
From the guardian.co.uk
He's a knuckle-dragger, a curser, a drinker of shots and cans and bottles with worms in them.
From the washingtonpost.com
Crew member Eric Rego was rescued by a nearby dragger.
From the orlandosentinel.com
The partial skeletal remains of Macara were caught in the net of a dragger near Billingsgate Shoal in 1985.
From the orlandosentinel.com
He's the sports world's most successful foot-dragger.
From the usatoday.com
Its not, its mainly one knuckle dragger.
From the thisishampshire.net
Unless you are a tap-dancer or chronic foot-dragger, chances are you don't suffer enough scuffs to keep it on hand.
From the lohud.com
Thatcher would have scorned the idea, but Britain the perpetual foot-dragger has a larger obligation in this than most.
From the businessweek.com
The 63-foot dragger was reported missing Feb.
From the orlandosentinel.com
More examples
Puller: someone who pulls or tugs or drags in an effort to move something
Trawler: a fishing boat that uses a trawl net or dragnet to catch fish
Dredging is an excavation activity or operation usually carried out at least partly underwater, in shallow seas or fresh water areas with the purpose of gathering up bottom sediments and disposing of them at a different location. This technique is often used to keep waterways navigable.
A term interchangeable with a fishing trawler boat. Draggers tow a large net.
A fishing vessel that catches fish by dragging a net along the ocean floor