Wan Sangkhan Lohng

If a character sleeps with people they shouldn't sleep with do they just get jizz stains everywhere?
Yes.

For stains that appear over clothing, will they actually stain the clothing in question, even when removed, or only appear when worn?
The stain won't magically disappear from the clothing but it can wash away from it, but not from the person.

Will there be something to prevent them from just hiding in their room the second the stains show up?
No, but the stain can appear anytime between April 13 and 14, so there's no telling if a character will get it or not until they do. Smugly commenting over the poor unfortunate ones while making tea at the pantry? Then, BAM STAINS.

Is this applicable to canon events that happen past a characters canon point, but that they've been told about by others?
Anything the character would rather hide can become a stain, so yes, if they know it then that applies.

How many stains can we have? I know people are doing multiple ones. Is there a set amount?
There's no limit on how many stains a character might have. On the flip side, the stains don't have to represent everything they regret either.

Will there be an IC post?
There will be no IC post for when the stains appear. But feel free to post your own post/log/group logs. Go wild!

What if there is something that they are hiding not just from others but from themselves?
If it is meant to be hidden, it can be a stain.