Talking loud on the phone while in a public area is surely a rude thing to do. It disturbs other people.
Many people eat with their mouth open, which creates eating noise. This is surely not a good thing for others.
Sometimes it's best to end the conversation, but some people like to have the last word even though there is nothing in conversation.
When going anywhere, you should mind the usage of perfume. Too strong or too much perfume is not good.
For kids, it's ok to say sir or madam, but with the same age, you should rather call pothers by their name.
If you know two people who are strangers to each other, you should introduce them first, before doing anything.
Asking a personal question about wealth, relationships or anything from your even closed one is a wrong and rude thing.