“What’s the opposite of a hot dog?”/“A cool cat.”

A hot dog riddle has been cited in print since at least 1969:
   
Q: What’s the opposite of a hot dog?
A: A cool cat.

   
A different form has been cited since at least 1980:
   
Q: What is the opposite of a cool cat?
A: A hot dog.

   
“What’s the opposite of a hot dog?”/“A chili dog” is a related riddle.
   
 
Wikipedia: Hot dog
A hot dog (less commonly spelled hotdog) is a food consisting of a grilled or steamed sausage served in the slit of a partially sliced bun. The term hot dog can also refer to the sausage itself.
         
Newspapers.com
10 February 1969, Tucson (AZ) Daily Citizen, “Fun Time—The Riddle Box,” pg. 25, col. 5:
What’s the opposite of a hot dog?
A cool cat.
 
Newspapers.com
5 December 1972, Gastonia (NC) Gazette, “Mini Jokes,” The Mini Page sec., pg. 3, col. 1:
What’s the opposite of a hot dog?
Ans. A cool cat.
 
Newspapers.com
18 September 1974, Austin (TX) American-Statesman, “Tell Me Why,” pg. 43, cols. 5-6:
What is the opposite of a hot dog?
A cool cat.
   
Newspapers.com
8 January 1980, St. Louis (MO) Post-Dispatch, “Jokes by You,” pg. 5D, col. 6:
Q: What is the opposite of a cool cat?
A: A hot dog.
Belinda Vitale
 
Google Books
Rover’s Riddles:
A joke and riddle book

By Jean Rudegeair
Yellow Springs, OH: Antioch Pub. Co.
1983
Pg. ?:
What is the opposite of a hot dog?
A cool cat.
 
Twitter
gーdraggin’
@lh3e
O.o? Hahaha RT @MoLteaser: what’s the opposite of a ‘cool cat’? - A ‘hot dog’ - get it? get it? HAHAHAHAHA
8:53 AM · Apr 6, 2010·Twitter Web Client
     
Twitter 
Sami.
@NYCGOTCAKE
whats the opposite of cool cat??—-Hot dog lol.
2:10 PM · May 29, 2010·Twitter Web Client
 
Twitter
John
@jordan_sanberg
Opposite of dog=cat
Opposite of cool=hot
Hot dog=cool cat
Boom mind blown.
12:55 PM · Jan 14, 2013·Twitter for iPhone
     
Twitter
HelloKaylie
@hellokaylie
davy-babes: COOL CAT IS MEANT TO BE THE OPPOSITE OF HOT DOG http://tmblr.co/ZnvIwwcQqAh5
10:45 PM · Jan 22, 2013·Tumblr
 
Reddit—Showerthoughts
Posted by u/antippson April 17, 2015
A hot dog is the opposite of a cool cat.
   
Reddit—Showerthoughts
Posted by u/Supposedpuppy123 March 9, 2016
The term “cool cat” is the opposite of “hot dog”
 
Twitter
Keegan Dunn
@dwarfkeeg
The opposite of a hot dog is a cool cat. This is all.
9:55 PM · Dec 12, 2020·Twitter for Android