We didn't actually think she had it in her, but the world's most rapidly maturing 15-year old, Miley Cyrus, is behaving like, well, a 15-year old for once. Just as reports surfaced that her rival in tween porn and Disney affection Selena Gomez may be dating Cyrus' ex-boyfriend, we learn that the Battle Of The Tweens has been going on far longer than we thought. About a month ago, the wet t-shirt contestant decided to team up with her BFF and film a YouTube video mocking Selena and her partner in underage midriff-baring crime, Demi Lovato. Have we lost you? Not to worry! The only two things you really need to know before watching this oddly hilarious clip are: we're slightly worried Miley has found her daddy's liquor cabinet, and Demi Lovato is the next Demi Moore.The NY Daily News is reporting that Gomez, the sultry-ish star of The Wizards Of Waverly Place , has been dating yet another 15-year old, singer Nick Jonas. As many of you may know (however embarrassing it is to admit), Jonas is the rumored intended recipient of most of Cyrus' kissy-face iPhone photos and pouty shower shots that hit the Internets recently. While Jonas is admittedly cute in an adolescent John Mayer sort of way, we don't see why a break-up with the kid should prompt Miley into such bitter antics. Making fun of Gomez and her alarmingly sexy best friend / fellow Disney star Demi Lovato in this clip, Cyrus drops some low-blows about the gap in Lovato's teeth (one that has since been fixed) and the fact that Lovato wears a touch of black make-up (and looks just fine in it). However, the attack seems to be backfiringl, mainly because Miley — who frequently succumbs to giggle attacks and slurring throughout the vid — made her rep as the good girl next door and not as a conniving backstabber (or, for that matter, as an burgeoning anti-Semite with her use of the word "scheisty"). Fasten your seatbelts, it looks like we have another Lohan vs. Duff feud brewing as we type.