The Say What app is essentially a video dictionary, similar to the website Urban Dictionary. Users have a variety of phrases to choose from, like duck face and throwing shade, and are asked to make short video clips to creatively demonstrate what the terms mean. Spanish and Mandarin slang words are also included, so there is a multicultural education to be gained from the crowdsourced video dictionary app.
The Internet and more specifically social media are having an accelerating effect on the way language and slang develop. Instead of phrases slowly becoming integrated into a more wide-spread lexicon, viral videos and similar content mean new terms can become popular extremely quickly. The expression 'on fleek' is an example of this, which originated in a Vine post.