This painting is called Kneeling Nun, by Martin Von Meytens, an Austrian painter who happened to be a protestant. The front of the portrait is the one of a seemingly pious nun who seems to be taking up her duties on prayer, with another nun behind her looking very fixated on...what if we turn the portrait and see what she's looking at?...Oh! Good heavens!
Yep. If you actually look at the reverse of this portrait, you'll see a complete image exposing another perspective that suddenly parodies the catholic devotion, having the painting turn into a sapphic tale. As a catholic, I gravitate naturally towards everything that's ironic and this was just too delicious to ignore.