A strange mist hangs over small, random parts of Diagon Alley on Tuesday, August 28th, lasting all day but disappearing at 11pm. It shimmers with an oily haze, hanging just around waist-high. There are no spots where it can not be passed by without touching, but those who don't bother and just walk right through will wake up the 29th with an unpleasant feeling, of something just not right. They will be unable to shake this feeling all day; in fact it grows worse, and a physical ache is felt sometime after 5 pm, depending on when they encountered the haze. When they awaken on the 30th, they will be in for the surprise of their life- they've swapped genders! This will last for the 30th and the 31st. On the 1st of September, they will awaken themselves once again, but the soreness from the 29th will be back until the following day.
The Ministry will spend a month investigating this matter, but find no conclusive evidence.