Laws regarding public behavior can vary depending on your location, as they are typically governed by local ordinances and regulations. Yelling at random people on the street through a megaphone could potentially be considered a form of disorderly conduct, public disturbance, or harassment, which is generally not legal in most places.
These laws are in place to protect public safety, maintain order, and respect individuals' rights to privacy and peaceful enjoyment of public spaces. If your actions are causing distress or interfering with the rights of others, you may be subject to legal consequences.
It is essential to be aware of and follow the laws and regulations in your specific area. If you have any doubts or concerns about the legality of certain actions, it is best to consult with a local legal professional who can provide accurate advice based on the laws in your jurisdiction.