Bubble porn is where a non-nude photo or video gets a swiss-cheese-like opaque overlay that gives the illusion of nudity. Since its meme heyday, the practice, known as bubbling, now uses translucent overlays that make the effect even more striking.
The idiosyncratic etymology “Mormon porn” does not seem to have caught on. Bonus videos: the effect in action is even more NSFW:
• Mormon Porn / Bubble Porn (h/t Calpernia Addams)