What should I get for my girlfriend's birthday?

You can send roses, lipsticks, bags and so on.

Birthday, Chinese vocabulary, as its name implies, refers to the day when a person is born and the day when he turns one year old every year. But folklore in some places believes that this is also the mother's "Good Friday". Because the technology in the past was not as fast as it is now, there is a saying when a mother gives birth to a child that "one foot is in the coffin and the other foot is outside the coffin". So they think that on that day, they should give priority to filial piety to their mothers.