If you don't think this movie funny
Maybe I didn't find it all that funny myself.
Now try to imagine every scene and bit of text is there in the sole purpose of being as tasteless and being as unconventional as possible.
this movie = clear winner.
I don't get that until the ending song. Then I wanted to rewind and watch it again. But I didn't! Because everything I've just watched is now in my memory and I can pass it in my mental revue. Now it's making sense and it's actually funny.
In other words: This movie starts to be funny the moment it's done