What is the ruling on the presence of obscene words like "idiot" and "stupid" in movies, and swearing "by the right of such-and-such" while the heart denies and dislikes the utterance, but one laughs upon hearing "idiot" and "stupid"? Is there sin in that?

Addressing a person with disdainful and demeaning expressions is considered cursing and reviling, which is forbidden in Islamic law, because the Prophet, peace and blessings be upon him, said: "The believer is not a slanderer, nor a curser, nor an obscene person, nor a foul-moutmouthed person," and "Insulting a Muslim is wickedness, and fighting him is disbelief." It is forbidden to insult a Muslim without a legitimate Shar'i reason. It is not permissible to listen to insults while being pleased with them. However, the listener is not sinful merely by listening if they are not pleased, especially if they show disapproval. If the person being insulted is unknown, then listening to the insult is not forbidden, just as backbiting is only considered for a known person, and the saying "There is no backbiting for an unknown person" is correct in its meaning, provided that it does not lead to searching for or identifying them.