>>41471Basically, it's a gloryhole. Some hentai images of gloryholes would should show a picture of the girls face on the wall. Eventually, people would draw pics where instead of a normal gloryhole, it would be girls sticking their boobs and butts in walls, and, eventually, fat ass bellies. Basically, some people find it hot because of the implication of a hot girl behind the wall and only being able to see a small part of her. Don't know if I explained that well, but yeah