Are NSFW headcanons allowed?
I think it depends on what sort of NSFW content you are going for…
NSFW Language - should be okay… just make sure to label it up very clearly as ‘NSFW’ (and if there is a ton of NSFW language then use the ‘spoiler’ tags too.)
Images of nudity - no.
Images like those found in ‘Beautiful Women / Men’ NSFW threads - probably best to label it as ‘NSFW’ and use the spoiler tags as above for the actual content.
Images of people having sex - no.
A little more on NSFW content on the site (including graphic depictions of violence, death, etc)