As per title, the movie is about vulgar humour. If you're not a Cantonese speaker and don't know a bit about HK culture it'll be hard to get the jokes. Even the director and main protagonist Chapman To said so themselves in an interview: they did the movie partly to spite mainland netizens who made fun of them for arguing with Weibo netizens when they can't even speak Mandarin, in return they wanted to make a movie that these people won't be able to understand. There were a few pretty good scenes (such as the scenes with Brother Tyrannosaurus, which could be found on YouTube), but overall it's an okay comedy.