Song heard in Maurices! Help!?

K so I heard this song in Maurices that was by a girl group at first I thought it was The Veronicas, but its not, but it sounded like them and the song said something like "she can be good, she can be bad", it was kinda poppy rockish? lol its the second time I've heard it and its drving me crazy I wanna know who its by! lol