The effect of treating an image as multi-layered paper, where ripping or removing one or more layers reveals something else (e.g. a successively less-dressed version of the character in the same pose, or the circuit board inside an electronic device).
Pixiv tag is "妄撮 (Mousatsu)", pin-ups of an extinct magazine called KING. Later, this plan was summarized in some photo books and these books made a big hit.
For characters that look like paper cutouts, use cutout.
For holes cut out of clothes, use cleavage cutout or side cutout.