“What do you get when you mix beans and onions?”/“Tear gas.”

It’s common knowledge that onions make one cry and that beans give one gas, leading to the joke:
 
Q: What do you get when you mix beans and onions?
A: Tear gas.
 
The joke has been cited in print since at least 1992 and is of unknown authorship.
 
 
Google Groups: rec.sport.basketball.college
Shaq and Brown
Jeffrey N. Burch
4/27/92
(...)
What do you get when you eat onions and baked beans???
Tear gas.
   
Google Groups: comp.unix.questions
ile (Input Line Editor)
Joshua A. Laff
2/18/93
(...)
What do you get when you eat onions and beans?
Tear gas.
 
Google Books
Everything I Know About Writing
By John Marsden
Sydney: Pan Macmillian Australia
1998
Pg. ?:
Q: What do you get from baked beans and onions? A: Tear gas.
   
Google Groups: at.gesellschaft.recht
Meldeamt
Clemens Haupt
1/11/00
(...)
. If I eat beans and onions, will I make tear gas?
 
Google Books
The Everything Kids’ Gross Cookbook:
Get Your Hands Dirty in the Kitchen with These Yucky Meals!
By Colleen Sell and Melinda Frank
Avon MA: Adams Media
2007
Pg. 43:
What can you make from baked beans and onions? Tear gas!
   
Google Books
Ultimate Book of Jokes:
The Essential Collection of More Than 1,500 Jokes
By Scott McNeely
San Francisco, CA: Chronicle Books
2011
Pg. ?:
Q: What sort of farts do you get by mixing beans and onions? A: Tear gas.
 
Twitter
Candida Tsasie
‏@Candida_Tsasie
Q: What can you make from baked beans and onions? A: Tear gas.
7:11 PM - 31 Aug 2014