Uncensored nudity in the "random posts" section of the top page
Straight-up genitals. This probably should not be allowed to happen even when a user isn't doing NSFW flagging properly and/or an instance is not enforcing it.
This was a link to a microblog with someone claiming to be an exhibitionist. Whilst I have zero problem with that, I do not want to have this open in the office (for example to look up a particular issue with a software or something) and have my boss walk by.