What is illegal to AirDrop?

What exactly is considered illegal to AirDrop? I understand that sharing copyrighted materials, malicious software, or illegal content is generally frowned upon, but are there specific laws or regulations that prohibit certain types of AirDrops? For instance, could I face legal consequences for inadvertently sending a harmless meme or joke to someone I didn't mean to? And what about sending promotional materials or advertisements through AirDrop? Are there any restrictions or limitations that I should be aware of?