Intellectually I never understand these degenerate kinks. It's not like you can really see anything. Even with a thong the good bits are covered, the angle will obscure everything, and there isn't anything physically to be seen. Add to this the terrible lighting, there is nothing sexual to be gained. Especially with porn so readily available. It's crazy.

The act itself must be the sexual pleasure and not the view resulting of the act itself. If anyone has a better explanation of the psychological aspect, please educate me.

I wouldn't be sad if anyone caught doing this had a horrible woodchipper accident. Any form of sexual retardation only gets worse with time.