I like your orgasm charm, that's really brilliant and fantastics! But I guess you need 'much' energy to give the receiver a mindblowing success! Then maybe they may ask...the actual act is much much easier than the charm...unless you are really occupied (i.e. with a dark wizard or a teacher around)

BTW, I really wonder if lubrication and stretching charms exist, though I understand these are fanfic and we should never question...however, without foreplay, the stories seem a little bit less hot and intense...as the emotions' exchange can paint really a good picture/image!