I'm curious if anybody out there had/has a dog stupider than the one I once had.
When I was a teen living on a farm in Minnesota, a stray Black Lab/St. Bernard cross (BIG dog) adopted us. He was friendly enough, but had a nasty habit of chasing cars. Only problem was that the cars he chased were going by at 60 mph on the highway in front of the house. Nothing would stop him from his all day, every day pastime, and he wore a path between the trees and the road.
One winter morning he finally caught one. We noticed his jaw was hanging a little funny and he was bleeding a bit, and the reason why became apparent when the owner of the car (a lawyer, unfortunately) stopped by and threatened to sue for damages because our dog hit his car. Apparently the dog had figured out how to lead his targets, and had stolen the left front hubcap with his teeth at high speed. Dad just laughed at the lawyer, and that was the last we saw of him. From that time on, though, the dog was tied on a long chain. If you released him, he'd instantly make a beeline for the highway and chase cars until he was too exhausted to elude capture.
Confinement didn't stop the stupidity, though. About a year or so later we found him dead. He'd wound himself around his tree so tight that he strangled himself -- too dumb to back up or go the other way. His loss was tragic, but at least he didn't reproduce and screw up the gene pool.