There was a joke in a recent episode of SouthPark (BlockBuster) that makes a direct reference to an adult movie. English is not my mother language, so I'm not sure if I've understood the joke completely. May I ask for a clarification here ?
Jokes which rely on the English language are at least implicitly on topic in the FAQ. The fact that it makes a direct reference to an adult movie doesn't change that.
Such a reference may make the question too localised, though.
Too localized: This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet.
The community can only make a judgement on that when the question is known.
The joke or its explanation may be Not Safe For Work which might cause some difficulties, although a reasonable academic discussion of the words used has certainly appeared before. It's possible to find some examples which are almost certainly NSFW: if your browser shows you the end of that link you can use your judgement about whether to follow it.