“Feta” is a cheese used in Greek salad. The plural of “fetus” is “fetuses” or “feti”—not “feta.” A joke was posted on the newsgroup alt.humor.puns on March 23, 2002:
 
“I’m glad ‘feta’ isn’t the plural of ‘fetus.’ If it were, I might have to stop eating Greek salads. (Gary Timm)”
 
     
Wiktionary: Feta
Feta (Greek: φέτα, féta, “slice”) is a brined curd white cheese made in Greece from sheep’s milk, or from a mixture of sheep and goat’s milk. Similar brined white cheeses produced in Europe are often made partly or wholly of cow’s milk, and they are also sometimes called feta. It is a crumbly aged cheese, commonly produced in blocks, and has a slightly grainy texture. Feta is used as a table cheese, as well as in salads (e.g. the Greek salad) and pastries. Most notable is its use in the popular phyllo-based dishes spanakopita (“spinach pie”) and tyropita (“cheese pie”), or served with some olive oil or olives and sprinkled with aromatic herbs such as oregano. It can also be served cooked or grilled, as part of a sandwich, in omelettes, or as a salty alternative to other cheeses in a variety of dishes.
 
Wiktionary: fetus
Noun
fetus (plural fetuses or feti)
1. (Canada, US) An unborn or unhatched vertebrate showing signs of the mature animal.
2. (Canada, US) A human embryo after the eighth week of gestation.
 
Google Groups: alt.humor.puns
Puns of the Weak 03/22/02
Stan Kegel
3/23/02
(...)
I’m glad “feta” isn’t the plural of “fetus.”  If it were, I might have to stop eating Greek salads. (Gary Timm)
   
Twitter     
Alyssa Al-Dookhi‏
@TheDookness
Replying to @mz_e
@mz_e My brain saw “feta” pronounced “feeta,” like a strange plural of “fetus,” and wondered where the hell you got those hashbrowns.
8:46 AM - 14 Apr 2009
 
Twitter       
Andrew Brunton‏
@ambrunton88
My love affair with Greek food is officially on hold until I can find out if feta is the plural form of fetus.
12:34 PM - 13 Feb 2014
 
Twitter 
Sarah Vanderson‏
@sarahvson
just read the phrase “hummus and feta” as “human fetus”...dyslexia at its most hilarious #helpmeimdumb
12:43 PM - 7 Apr 2014
 
Twitter
Tilly‏
@kingconsuela
Feta and hummus mushed together makes fetus, coincidence? I think not
2:49 PM - 11 Jul 2014
 
Twitter 
Capt.QuartzGhostcoat‏
@nosetimes4moms
I thought feta cheese was just cheese made from more than one fetus
1:51 PM - 19 Jun 2016
 
Twitter
Mark DeWitt‏
@maxhostile
Contrary to popular belief, “FETA” is a type of cheese, and NOT the plural of “FETUS”
11:20 PM - 7 Sep 2016
 
Twitter
Ghost‏
@marissalissala
My phone auto corrected feta (cheese) to fetus
10:00 PM - 13 Mar 2017
 
Twitter
rucha‏
@ruchdesh
Just tried convincing my sister that feta cheese came from fetus’
12:30 AM - 1 Aug 2017