Glow Foam is a GIF of a bowl in which shaving cream is mixed with UV reactive facepaint, while under a blacklight. Most people who see the Glow Foam GIF get hungry and want to eat it.
The GIF is originally from a youtube video: https://youtu.be/EQw1b5g1uC8, and was submitted as a GIF by PhotoandGrime on Imgur first: http://i.imgur.com/ARL6oWs.gifv.
Next, it was posted on the subreddit /r/awesome: https://www.reddit.com/r/awesome/comments/3ira3n/glow_foam/
Other subreddits started to repost it (https://www.reddit.com/r/woahdude/comments/3itchr/glow_foam/?ref=search_posts and https://www.reddit.com/r/oddlysatisfying/comments/3it6vo/glow_foam_rawesome/), and users started to wonder what it was made of, and why they wanted to eat it. Bangarang Peter Pan references were made, and many link the Glow Foam to their childhood memories of the film Hook, in which the lost boys eat colourful food in the food fight scene.
9gag took the GIF from Imgur as well and uploaded it (http://9gag.com/gag/adpv1d2 and http://9gag.com/gag/aNKLvD0), after which other social media quickly followed. For example:
http://funnyjunk.com/Glow+foam/hdgifs/5669214/
http://rebrn.com/re/glow-foam-695566/
https://twitter.com/TMVtweetz/status/638517296751857664
http://www.skarro.com/featured/how-to-make-glow-in-the-dark-uv-foam-diy-tutorial-halloween-ideas/
The original GIF on imgur has been viewed 587,380 within the first 4 days. The first 9gag post gained over 20,813 points within 3 days.