It means their parents taught them nothing about respect. Its essentially a rude way to tell someone they are old news
it means that no one uses that item anymore. its not as common as it used to be.
they are shallow pigs
It means that something is out of fashion. Like if you bought last years most awesome top and wore it this year. Does that make sence?
people need to stop being so shallow and stop blame the little girls, blame the people or their parents who are influencing them to say things like this. Either they saw it on a T.V. show and are joking around with you or they really were influenced by other people. I think "that's so last season." is just something stupid ignorant rich people say to degrade other people about their way of clothes. People with shopping issues and how they handle their money.
It means they think you are stuck with old school ways of doing what you do, and they have a better idea so ask them what they have that's new, because it has to be good to succeed. Younger sometimes can be better, and we all learn something new everyday. Learning and teaching that age discrimination isn't very smart, either way you go.
What rude little girls! Flip your hair at them.