An onion rings riddle is:
     
Q: Why does Mr. Potato have a mobile phone?
A: Just in case Mr. Onion rings.
   
The joke was posted on Twitter by Sickipedia_Feed on April 16, 2013, and originated on the Sickipedia website.
   
“If you hear an onion ring, answer it” is a similar joke about onion rings.
     
     
Twitter
Poker Knave
@pokerknave2
Why did Mr Potato have a phone?
Just in case Mr Onion rings
2:17 PM · Apr 16, 2013·Twitter Web Client
   
Twitter
Sickipedia_Feed
@Sickipedia_Feed
Why did Mr Potato have a phone?Just in case Mr Onion rings. http://bit.ly/YQsiyp
2:18 PM · Apr 16, 2013·twitterfeed
 
Twitter
RN
@upminster13
Why did Mr Potato have a phone?
Just in case Mr Onion rings.
2:59 PM · Mar 4, 2014 from Havering, England·Twitter for Android
   
Reddit—Jokes
Posted byu/[deleted] December 12, 2017
Why does Mr Potato have a phone?
Just in case Mr Onion rings.
 
Twitter
Bob Kostic
@causticbob
Why did Mr Potato have a mobile phone?
Just in case Mr Onion rings.
7:00 AM · Dec 13, 2017·Twitter Web Client
       
1 September 2018, Daily Star (London, UK) [London (UK), pg. 22:
Why does Mr Potato Head carry a phone? In case Mr Onion Rings.
Grannie Fossie, Methilhill
   
Reddit—Cleanjokes
Posted by u/madazzahatter October 22, 2018
Why does Mr. Potato have a mobile phone?
Just in case Mr Onion rings…
   
YouTube
Why does Mr Potato Head have a mobile? In case Mr Onion Rings!
Apr 28, 2020
Krist Cookery
   
Twitter
QT@Anon
@QTAnon1
Why did Mr Potato have a mobile phone?
Just in case Mr Onion rings.
8:38 PM · May 26, 2020·Twitter Web App
     
Reddit—Dadjokes
Posted by u/Rav4xle June 7, 2020
Why did Mr Potato have a mobile phone?
Just in case Mr Onion rings.
 
Twitter
tis me. Nic
@tismenic70
Why does Mr Potato head carry a mobile phone?..
Apparently.. It’s just in case his mate
Mr Onion rings…
#tuesdaytitters
4:58 AM · Oct 6, 2020·Twitter for Android