It's Related to a prank.

Female Anime characters have always been a victum of losing their clothes infront of others. Whether it be ecchi, hentai, or just some slapstick comedy where they hit a male after ending up in an exposed situation with or without it being their fault in the first place. This story thread is for those who want to extend that situation in various ways (only excluding situations against the rules) and wanting to add a bit more embarrasment to their Heroine infront of those who will (possibly) enjoy it and make their day even worse than ever before.