“Why didn’t the dog want to play football?”/“It was a boxer.”

A dog riddle is:
 
Q: Why didn’t the dog want to play football?
A: It was a boxer.
 
The “boxer” pun has been cited in print since at least 2001.
 
     
Wikipedia: Boxer (dog)
The Boxer is a medium-sized, short-haired breed of dog, developed in Germany. The coat is smooth and tight-fitting; colours are fawn or brindled, with or without white markings, and white. Boxers are brachycephalic (they have broad, short skulls), have a square muzzle, mandibular prognathism (an underbite), very strong jaws, and a powerful bite ideal for hanging on to large prey. The Boxer was bred from the Old English Bulldog and the now extinct Bullenbeisser which became extinct by crossbreeding rather than by a decadence of the breed. The purpose of the crossbreeding was the wish to eliminate the excessive white color of the breed, and the necessity of producing thousands of dogs for one of the most popular breeds in the world. The Boxer is part of the Molosser group. This group is a category of solidly built, large dog breeds that all descend from the same common ancestor, the large shepherd dog known as a Molossus. The Boxer is a member of the Working Group.
 
CPFC BBS   
furry mascots and football jokes.     
Teaser
07-06-2001, 08:59 PM
(...)
Why didn’t the dog want to play football ?
It was a boxer !
   
Google Books
1001 More Cool Jokes with Glen Singleton
By Glen Singleton
Victoria, Australia: Hinkler Book Distributors
2002
Pg, 185:
Why didn’t the dog want to play football?
It was a boxer!
 
18 December 2002, Augusta (GA) Chronicle, “Read My Lips: Books Are Fun,” SC Neighbors, pg. 1:
Tre asked a friend, .“Why didn’t the dog want to play football?” The answer: “Because he’s a boxer.”
 
Google Groups: Humor Club
Humor & Sports
R.K.
11/12/05
-: HUMOR AND SPORTS ! ! :-
>>1. What tea do footballers drink ?  Answer: Penal-tea.
>> 2.Why didn’t the dog want to play football ?  —Answer: It was a boxer ! !
   
Google Books
Sports Jokes
By Hugh Moore
Edina, MN: ABDO Publishing Company
2010
Pg. 18:
Why didn’t the dog want to play football?
It was a boxer!
     
Google Books
The Mammoth Book of Really Silly Jokes:
Humour for the whole family
Edited by Geoff Tibballs
London, UK: Constable & Robinson Ltd
2011
Why didn’t the dog want to play football?
Because it was a Boxer.
 
Twitter
Lucky Score
@LuckyScoreNet
Why didn’t the dog want to play football
?
It was a boxer !
#Joke from #SportJokes in #Jokes, #Humor and #Satire
2:22 AM - 10 Apr 2018