"Lengthy Procession" joke

One afternoon, Peter was out raking leaves when he noticed a hearse slowly drive by. Following the first hearse, was a second hearse, which was followed by a man walking solemnly along. Following the man was a dog, and then at least 200 men walking in single file.
Intrigued, Peter approached the man following the second hearse and asked him who was in the first hearse.
"My wife," the man replied.
"I'm so sorry," Peter said. "What happened to her?"
"My dog bit her and she died," the man answered.
"Who's in the second hearse?" asked Peter.
"My mother-in-law," the man said.
"What happened to her?" inquired Peter.
"My dog bit her and she died as well," the man explained.
Peter thought for a moment, then said, "May I borrow your dog?"
"Get in line!" the man replied.