I think it's satirical on the way she is portrayed in the media. "Got a long list of exlovers" is the reference to the media claiming that she has had so many boyfriends in the past, "I've got a blank space baby" is her saying that it's the same story over and over but with different men. The part of the song when she says: "find out what you want, be that girl for a month, wait, the worst is yet to come", it is referencing the perception that many 'haters' hold that she is manipulative and evil and it means that she lures these men in to a relationship with her before revealing her true self leaving her unsuspecting boyfriends asking themselves, "oh my God, who is she?" Because to her "loves a game". Obviously in this scenario she is showing psychopathic tendencies that might make her ex loves"tell you [she's] insane" This song is a dig at her haters and how she is perceived by them which is made ironic due to the fact that in saying pretty much to the world that she's a crazy bitch/psychopath it has furthered her undeniable success. This this theory is made all the more plausible by the fact that she has recently released a song about the 'haters' hating. Obviously this is all just my opinion.