What is a silly law you can make up and what is your "reasoning" behind it? (Please don't reply something racist or sexist.) I'll go first. Every Friday, you can't say cool or awesome or great or anything similar. You have to saw yee-haw. Reason? It'll provide variety in conversations and people will think "oh, it's Friday."
Law: If you are a woman, you cannot ride a horse unless a physician deems that you are properly laced into your corset. Reason: A properly laced corset is integral to a woman's garb, especially if she's on a horse.