Swearing can put a funny spin on things.
The film "The King's Speech" is for the most part a very subtle character study, almost suited as a stage play. There's no violence, merely the blaring of an air raid siren As Lionel is driven to the building where the King is to give the titular broadcast. There's no nudity or sex. The "worst" we see is Duke and Duchess of York in some housecoats.
But amazingly, it has an "R" rating!
Why? There's a scene where Lionel discovers "Bertie" has less difficulties speaking when he utters a "coloful metaphor". So the speech therapist encourages the Duke to "let it out". "Bertie" rips loose with a string of curses that roll trippingly off his tongue without hesitation. It's rather quite silly as he rattles off various tenses of the "F" word as though called upon in a grammar class.
Yes, it was a short sequence with "bad" language that earned the movie its "R" rating, not for nudity, not for violence. So the ratings game can be quite arbitrary at times.