Know your meme: Reeeeee!
About
“REEEEEEE” is an onomatopoeic expression of intense rage or frustration typically associated with the Angry Pepe character and used by those who frequent the /r9k/ board on 4chan. It is meant to represent the unique croak produced by several species of frogs when agitated.
Origin
Certain frog species are known to produce a shrill scream noise to ward of predators when threatened.[12][13] On October 25th, 2009, the earliest known video of this behavior was uploaded by YouTuber ppparaone, which gained over 2.5 million views and 4,600 comments in the next six years (shown below). This video would later one become even more popular with a screenshot of a comment, and spread to humor content aggregator clickbait websites such as Buzzfeed [14] or Smosh [15].
The earliest known archived use of the onomatopoeic version of the scream was submitted to 4chan’s /r9k/[7] board on December 27th, 2014, featuring an image of Pepe the Frog accompanied by the message “REEEEEEEEEEEEEEEEEEEEEEEEEEEEE”
http://knowyourmeme.com/memes/reeeeeee?full=1