“Cough fart ... When someone coughs to hide a fart with devious intent” was entered in the Urban Dictionary on December 2, 2010.
 
The 2019–20 coronavirus outbreak reversed this. “For the first time in history we cover our coughs with farts in public” was posted on Twitter by Living Sarcasm on February 23, 2020. “Overheard on the street: ‘Once upon a time you had to cough to cover up your fart on the metro. Now you have to fart to cover up your cough.’ Sorry. Humour is my coping mechanism. #coronavirus” was posted on Twitter by Ilse van den Berg on February 24, 2020.
 
“Jackie Chan:‘Back in the past we used to cough to cover our farts, now we have to fart to cover our cough’” was posted on Twitter by Asaru later on February 24, 2020.
 
“Hide a fart” was used slightly later than “cover up a fart.” “Crazy times we are living in. I used to cough to hide a fart. Now I fart to hide a cough” is a related saying.
 
     
Wikipedia: 2019-20 coronavirus outbreak
The 2019–20 coronavirus outbreak is an ongoing global outbreak of coronavirus disease 2019 (COVID-19) caused by the SARS coronavirus 2 (SARS-CoV-2). The disease was first identified in Wuhan, Hubei, China on 1 December 2019, spreading to every province-level administrative division of the country by 29 January 2020. On 30 January, the World Health Organization declared the outbreak a Public Health Emergency of International Concern following an increase in the number of cases outside China.
 
Urban Dictionary
Cough fart
When someone coughs and lets out a fart either accidentally or strategically at the same time.
When someone serendipitously farts while coughing and the cough masks the sound of the fart.
When someone coughs to hide a fart with devious intent.
(...)
by SweetpeainSF December 02, 2010
     
Twitter   
Living Sarcasm
@SarcasmLiving
For the first time in history we cover our coughs with farts in public
7:29 PM · Feb 23, 2020·Twitter for Android
   
Twitter
Ilse van den Berg
@ilse_vdberg
Overheard on the street: “Once upon a time you had to cough to cover up your fart on the metro. Now you have to fart to cover up your cough.” Sorry. Humour is my coping mechanism. #coronavirus
7:08 AM · Feb 24, 2020·Twitter for Android
 
Twitter
Asaru
@Asaru09
Jackie Chan:”Back in the past we used to cough to cover our farts, now we have to fart to cover our cough”
Jackie Chan:”Back in the past we used to cough to cover our farts, now we have to fart to cover our…
Maaaan that’s deeeep
dankingnews.com
7:11 PM · Feb 24, 2020·Twitter for iPhone
   
Twitter
Krissy
@Kristine_Lotus
Replying to @liamgallagher
We used to cover our farts by coughing.. now we’d rather fart to hide the cough
12:14 PM · Feb 27, 2020·Twitter for Android
   
Twitter
BURGER
@HA_HAMBERGER
“We cough to cover fart,Now we have to fart to cover cough”
-Jackie Chan
10:16 AM · Mar 2, 2020·Twitter Web App
   
Twitter
ooN ooN ʎʇɥɓnɐN
@TrishaPhillipss
Morning all..
The sun is shining! Sun with face
You know, before the Coronavirus we coughed to cover a fart,
Now we fart to cover a cough! Winking face
4:32 AM · Mar 8, 2020·Twitter for Android
 
Twitter
Paul Harris
@Baoluo_Hali_si
Before Corona virus I’d cough to cover a fart.
Now I fart to cover a cough
#COVID2019uk #coronavirusuk
6:37 AM · Mar 10, 2020 from Canvey Island, East·Twitter for iPhone
 
Twitter
Jokes UK
@jokesuk
Before corona virus I’d cough to cover a fart…
Now I fart to cover a cough!
3:34 PM · Mar 10, 2020·Twitter for iPhone
 
Reddit—Britishproblems
Posted by u/Mombo1212 March 10, 2020
I remember when I would cough to cover a fart. These days I have to fart to cover a cough.
   
Reddit—Showerthoughts
Posted by u/richymc9786 March 10, 2020
Last year people were coughing to hide farts but this year people are farting to hide coughs
 
Twitter
The Dad Joke Man
@DadJokeMan
People used to cough to cover up a fart, now they fart to cover up a cough!
#WednesdayThoughts #coronavirus
3:03 AM · Mar 11, 2020·Twitter for iPhone
     
Reddit—3amjokes
Posted by u/Suave_Sidd March 11, 2020
Before corona virus I’d cough to cover a fart…
Now I fart to cover a cough!
 
Reddit—Jokes
Posted by u/HIGH-LION March 11, 2020
Before Corona…
I would cough to cover a fart… Now I fart to cover a cough