Q:

Profanity on the main page

On linguistic sites, for example on Русский язык, it is rather appropriate to discuss obscene vocabulary. We on rus.SE use a special tag to indicate this kind of stuff (in order to allow some people to ignore these questions) but anyway there is a need to hide somehow these discussions. Why? Let me show.
Our site is really useful for pupils of all ages, confessions and views, hence we have children and teenagers as a huge part of users. Now imagine a 15-year-old schoolboy who opened the main page and saw these titles:
Пи..дабол или пи..добол: как правильно? (Which spelling of the extremely obscene word is correct?) 

The first part "п..да" of the word "пи..дабол" is translated as "c.nt"

Et cetera.
Obviously, it can and—moreover—it will repulse a huge number of visitors. What if a parent, who is not a linguist, notice his or her child reading such indecent topics? Enough said.
To sum up, we, language sites, need an option to get the posts tagged obscene-language automatically hidden from the main page. Those who want to see the discussions in question should be able to disable the ignore mode. Probably one should be asked during the registration process if he or she wants the obscenity to be demonstrated. Users who already have accounts may be notified by a Meta post or something special (like an email). I also think that a pop-up notification suggesting two options ‘Yes, show me this stuff’ and ‘Do not!’ is a suitable solution. It can be shown to new visitors, just like one about cookies. 
From comments:

A moderator should be the one to put the tag, and only moderator, otherwise it gives too much power to ordinary users, even spammers who will use it to hide their spam from public view, while it will likely still be linked from the source code and increase their Google rank. 

Maybe it is not the only possible way. Why not to allow something like spoilers in titles?

A:

Practically - this seems like something that folks didn't take into account when designing the platform. Most sites have a no profanity rule enforced to various levels - and that sort of content filtering is usually not needed. We've often reminded folks, anything we say on SE is visible to the world. Admittedly, this can be a little troublesome at times.
In addition, we're trying to explicitly use a meta tag as a content filter of sorts... which is a bit off, and a bit of an off label use of a tag.
In a sense - we're trying to special case a feature to solve a moderation/community feature most sites have solved. We don't allow profanity on most sites specifically for the chance of offense, to the point where much salty language can be a single flag nuke in comments. 
Within the current framework - a "soft" workaround might be the use of spoiler tags and warnings - so people need to hover over said language. 
WARNING SALTY LANGUAGE

 there's no salt emoji. I'm shocked.

If we're doing this - it shouldn't be a specific tag - it should be a designation for a post, since other sites may have specific requirements different from yours. There's a few philosophical and practical considerations here. On SE - posts are visible by default, and that's always been the policy here. We'd be (presumably) hiding posts from new users, unless they're registered, and explicitly set themselves to view it.  This is.. something that typically isn't done 

A:

First of all, you need to determine if it was trolling. If so, users (or moderator) can close/delete the question. 
Secondly, what's wrong if young (actually, the age doesn't matter) people will see this questions? I mean, even if there are offensive words in the question (but the question itself is polite), they still are the part of the language.
And the last one...

Писать и какать — однокоренные слова? (Do pee and poo share the same
  root?)

What's wrong with it? It's not offensive, it doesn't have obscene vocabulary. You can try to vote for closing, but there is no reason to hide/delete something in this question.
UPD: there is no need to add special tag. SE network sites are moderated by a community. If community doesn't like the question it will be down-voted/closed/deleted naturally.

