The background is that somebody seems to have hacked her Snapchat. Here is the story without any pics.
A gallery (imgur)
A gallery (fappenism)
A gallery (thefappeningcelebs)
A gallery of these and other Demi pics (fappeningbook)
I don’t know who the “chuckling squad” is, but they seem to be the responsible parties, and have added their comments or watermarks everywhere.