[quote=@ImportantNobody]
Let's say a male character magically (and likely permenantly) changes to a female.
...which bathroom would be the correct choice? XD

I bet he disguises himself as male again at first but then his disguise comes off and wacky hijinks ensure as people think he's a perverted woman sneaking into the male bathroom. He probably ends up practically forgetting his previous identity, though.
[/quote]

That or completely slips his mind he's a woman, stress does that, and walks instinctively into the men's room without batting an eye until he's 'escorted' out or worse.