As a few people have already said - she's just trying to fit in. It must be hard for her being the only new person in your group and she's obviously trying to get you to like her. Unfortunately, through trying to have something in common with you all she's unintentionally annoying you.
As she's probably already feeling vulnerable about being the "newbie", it would be a bit harsh to say something to her straight out - even if it is in a jokey manner, she'll probably still feel hurt. Although this sounds a bit like what you'd do to train your pet dog - try praising her for being herself e.g. laughing at jokes she's thought of herself, telling her her "own" new top looks great. Hopefully, she'll soon recognise that your group respects each person's individuality and she'll be more comfortable with her own image/personality.
Laura xxx