“What are the two things you can’t eat for breakfast?” (riddle)

“What are the two things you can’t eat for breakfast?” is a classic food riddle. “Lunch and dinner” is the answer.
 
“You know, there are two things that I can’t eat for breakfast—lunch and dinner” was told on a 1951 episode of the television situation comedy I Love Lucy. However, the joke probably dates to a vaudeville routine many years earlier.
 
“What can you never eat for Thanksgiving dinner?”/“Breakfast or lunch” is a similar riddle.
 
   
TVLand—I Love Lucy
The Benefit
Episode: 013 | Aired: December 31, 1951
Lucy resorts to womanly wiles to get Ricky to sing at a women’s club benefit. Ricky is reluctant at first, but Lucy tricks him into agreeing to sing and dance with her at the function. In this episode Lucy and Ricky reprise a classic vaudeville routine, ‘Underneath the Bamboo Tree.’
 
Springfield! Springfield!
I Love Lucy (1951) Episode Scripts
013 - The Benefit
(...)
You know, there are two things that I can’t eat for breakfast—lunch and dinner.
 
16 October 1972, The Daily Courier (Connellsville, PA), the Mini Page, pg. 3, col. 1:
Q. What two things can’t you ever eat for breakfast?
A. Lunch and dinner.
Lorrie Lint, Alverton
 
28 February 1987,Mobile (AL) Register, “A Little Bit of Humor,” The Bubble Gum Rapper, pg. 1, col. 2:
Tom: There are two things I can’t eat for breakfast.
Tim: What are they?
Tom: Lunch and dinner.
 
28 April 1990, The Times (Trenton, NJ), “Good Humor,” pg. B1, col. 1:
“Tell me two things you can never eat for breakfast.”
“Lunch and dinner.”
 
Google Books
My Daddy Died and It’s All God’s Fault
By Sue Holden
Illustrations by Renée Graef
Dallas, TX: Word Pub.
1991
Pg. 4:
“Name two things you positively can’t eat for breakfast?”
“I don’t know. What?”
“Lunch and dinner!”
 
Twitter
Joel CommVerified account
‏@joelcomm
@scott_fox nailed it - the two things you cannot eat for breakfast are lunch and dinner
5:49 PM - 3 Dec 2008
 
Twitter
RED
‏@Redconcept13
The only two things you shouldnt eat for breakfast are lunch and dinner.
2:41 AM - 4 Sep 2013