As you can see from the various answers below, there are different interpretations of what is rude. Generally, rude behaviour does not involve consideration for others feelings. However, cultural and situational differences can change the expectations of what is acceptable. For example, in some societies, brushing against a person is a minor intrusion and in others it is a very rude invasion of one's personal space.
I would say rudeness is not really a big issue with me but jumping the line for example is a mild form of rudeness.
I'm just fed up with trying to get my brother to play properly. He's always saying bitter remarks and "that's rubbish" when I give him my game to play with for example - it reflects back at you and you ask yourself why does he annoy me whenever he doesn't like it? Its not my fault that he is playing that game. It might sound mundane but it feels like you give a nice present and then enjoy it - and then return it to you and say that was crap I'd say get stuffed.
when u say somethin mean to a grown up like u dress like crap.
When ur words and behaviour r insensitive to other people's feelings then it can be termed as rudeness.
If someone is talking with you and you cut them off saying "I don't care." or "I don't care about !" that is rude. Don't even talk to with them anymore then if you don't care about what they have to say. I hate when people do that to me. Also, saying "Whatever..." or "Whatevs".
Just being impolite or offensive.
Being inconsiderate or hurtful , when deliberate . For the polite person, rudeness by the ignorant or untrained is not remarked upon , as being critical is in itself a form of rudeness. These people you ignore , or give them your back til they get the hint their behavior or speech is not acceptable.[ This does not apply to parents and teachers, in their proper pervue. ] .