“When you have nothing to say, say it on Twitter” is a jocular one-line Twitter saying that has been printed on images. Twitter messages are only 140 characters, so one can’t say much. The saying was popularized by a May 2008 cartoon.
 
“When you have nothing to do, do it on Facebook” is a related saying.
     
 
Wikipedia: Twitter
Twitter (/ˈtwɪtər/) is an online news and social networking service where users post and interact with messages, “tweets,” restricted to 140 characters. Registered users can post tweets, but those who are unregistered can only read them. Users access Twitter through its website interface, SMS or a mobile device app. Twitter Inc. is based in San Francisco, California, United States, and has more than 25 offices around the world.
   
Geek and Poke CARTOONS
The Web 2.0 Slogan Of The Month - May
May 3, 2008 12:29:00 AM
WHEN YOU HAVE NOTHING TO SAY, SAY IT ON TWITTER (Cartoon.—ed.)
 
Twitter
Bas van de Haterd‏
@bvdhaterd
when you have nothing to say, say it on twitter!
4:21 AM - 3 May 2008
 
Twitter
Kiran Denniz‏
@KiranDenniz
When you have nothing to say, say it on Twitter! http://tinyurl.com/5fhfdf
4:45 AM - 3 May 2008
 
Twitter
Geeks are Sexy‏
@geeksaresexy
Re-tweeting @brianshaler : When you have nothing to say, say it on Twitter - http://tinyurl.com/5fhfdf
9:11 PM - 4 May 2008
     
Twitter
Florian Wagner‏
@Tabasco75
bestimmt alt, aber gut: When you’ve got nothing to say, say it on Twitter!
When you’ve got nothing to do, do it on Facebook!
5:12 AM - 5 May 2008
 
Twitter
Bica‏
@bicaaa
“When you have nothing to say, say it on Twitter”
4:11 AM - 17 Aug 2009
 
Twitter
Lyrical Treasure!‏
@TreasuredLyric
I have nothing to say, so I’m gonna say it on twitter.
11:39 PM - 10 Apr 2017