Good grief, everyone needs to calm down. If I press my chin closer to my neck with my hand, my skin is going to fold up on itself, too. Her arm probably is pressed against her body--from what I can see, it looks like she's very skinny.
(Just imagine someone taking one photo of yours from Facebook at random and trying to deduce your weight from it. Basically, I feel that one photo is not necessarily a fair piece of evidence from which to judge.
)