Botanically, a tomato is a fruit. “If tomatoes are technically a fruit, is ketchup technically a smoothie?” is a jocular line that has been printed on posters and e-cards.
 
“Today, I realized that if a tomato is a fruit, wouldn’t that make ketchup a smoothie?” was cited on Twitter on September 26, 2010.
 
“If a tomato is a fruit, then ketchup is a jam” and “If an avocado is a fruit, is guacamole a smoothie?” are related sayings.
 
   
Wikipedia: Tomato
Fruit versus vegetable     
Botanically, a tomato is a fruit—a berry, consisting of the ovary, together with its seeds, of a flowering plant. However, the tomato is considered a “culinary vegetable” because it has a much lower sugar content than culinary fruits; it is typically served as part of a salad or main course of a meal, rather than as a dessert. Tomatoes are not the only food source with this ambiguity; bell peppers, cucumbers, green beans, eggplants, avocados, and squashes of all kinds (such as zucchini and pumpkins) are all botanically fruit, yet cooked as vegetables. This has led to legal dispute in the United States. In 1887, U.S. tariff laws that imposed a duty on vegetables, but not on fruit, caused the tomato’s status to become a matter of legal importance. In Nix v. Hedden, the U.S. Supreme Court settled the tariff controversy on May 10, 1893, by declaring that the tomato is a vegetable, based on the popular definition that classifies vegetables by use—they are generally served with dinner and not dessert. The holding of this case applies only to the interpretation of the Tariff of 1883, and the court did not purport to reclassify the tomato for botanical or other purposes.
   
Twitter
Justin Bieber
‏@BieberSoCal1
Today, I realized that if a tomato is a fruit, wouldn’t that make ketchup a smoothie?
10:58 PM - 26 Sep 2010
   
Amirite?
Sep 27th 2010
Jman
If tomato is a fruit doesn’t that make ketchup a smoothie, amirite?
 
Twitter
Elizabeth Marie
‏@MargA_Licious
Sister: Since a tomato is a fruit, does that mean ketchup is a smoothie? http://tumblr.com/xgxjtv6zg
11:39 AM - 27 Sep 2010
 
Twitter
Vikki StClaire.
‏@vikkeh
If tomatoes are a fruit, Is ketchup technically a smoothie?
5:27 AM - 22 Oct 2010
 
Twitter
enzi ☆
‏@negativenzi
IF TOMATO IS A FRUIT - ISN’T KETCHUP TECHNICALLY A SMOOTHIE? http://tumblr.com/xjkmytfnt
6:29 AM - 24 Oct 2010
 
Google Groups: alt.usage.english
Hon my way to Georgia?
John Varela
11/10/10
Re: tomato: fruit *and* vegetable (was: Meaning of “dialect”)
(...)
Question: if tomatoes are a fruit, is ketchup a smoothie?
 
Natural Health ezine
So Is Watermelon A Fruit Or Vegetable?
February 21, 2010 by Bob
(...)
COMMENTS
Dave says:
February 4, 2011 at 10:20 pm
This whole vegetable vs fruit thing is stupid. It depends on if you are speaking about common definition, botanical definition, legal definition, etc. For example, the common definition of a tomato is a vegetable. Botanically, it is a fruit. Legally (in the USA) it is a vegetable (there was a Supreme Court ruling, Nix v. Hedden).
 
So yeah, go ahead and call it a fruit, but realize that unless we’re biologists, that makes ketchup a smoothie.
 
Google Books
Little Dead Riding Hood
By Amie Borst and Bethany Borst
Provo, UT: Jolly Fish Press
2014
Pg. 37:
If tomatoes are a fruit, then ketchup is a smoothie.
   
Twitter
Laugh Please
‏@tfunnysaying
If tomatoes are technically a fruit, is ketchup technically a smoothie?
9:30 PM - 16 Oct 2014