I've often wondered and I think it could be Dixie, not sure though, would love to know the situation/setting. It always strikes me as it's a public bath's changing room, the fella next to her doesn't seem to realise whats going on so it looks to be kind of candid/under cover.
My dream scenario is she's going swimming, some lucky perv with a camera has dared take a pic of her and she's responded as in the pic, i.e. instead of kicking off she knows she's making this pervs day/month/year and she's playing up! That expression.....
Floors me.