![barefoot bath bath_kick bathing bathtub between_toes bubble commentary_request foot_hold hanji_(hansi) hatsune_miku horror_(theme) kagamine_len kagamine_rin leg_lift legs letterboxed no_humans partially_submerged rubber_duck shiteyan'yo smile vocaloid water what rating:s score:2 post #615663](/cdn_image/preview/e8/0b/e80b640906f9de0044dc8e78e56de0a2.jpg)
Contrary to the what tag, Posts that you do not understand at all and leave you thinking, "WHY would you do that?"
Less that they leave you in confusion more that you just do not understand why they would do it. Similar to unlikely crossovers; you can see that they did it so it would not categorize as 'what', but would still qualify as "Why?".
Its pixiv equivalent are どうしてこうなった OR どうしてそうなった.