Maybe it stayed put just nicely when standing upright, but after sitting down -- not so much?
Edit: Holy shit! Must be the first time ever a YouTube comment was actually useful - https://vgy.me/xnFPf7.png
Emblu (model, I believe his sister) on instagram.
Edit: Apparently that's not his sister, but he still takes half naked photos of his sister (he's from Alabama). Thanks /u/iwanttowatchyoupoop & /u/apetresc for research.
I was intrigued by this image.
The earliest instance that I was able to find with either Google or Tineye was a reddit post dated July 3, 2011.