This is the real-life "Stacky," wife of artist and fan of growth and inflation, Tlink. Tlink posts a number of illustrations based on his wife (former girlfriend) over on his DeviantArt page. Also, if you click the "Stacky" tag up at the top of the screen, you should see most of the illustrations that have been posted here.
http://lakehylia.deviantart.com/
Who is this girl???