As if there aren't enough screaming fans at a Taylor Swift concert anyway, add a fringe-haired superstar and the noise becomes out of control!!!!    Last night, Taylor was performing the first of four shows at Los Angeles' Staple Center on her "Speak Now" Tour when Justin Bieber surprised everyone by walking out on stage!    Together, the two sang Bieber's hit song "Baby."   After the song, the Biebs made a quick exit, but Taylor later tweeted, "You think you've heard LOUD screaming in your life," she wrote. "Then @justinbieber comes out and does a surprise song during your show. Woah. Unreal."    Justin tweeted back, "@taylorswift13 we should do that more often. :) great show! #muchlove"   Could this be the beginning of a future duet from the pair?     Before last night's show, Taylor called into Ryan Seacrest's radio show to talk about a recent "wardrobe malfunction."   At a show last week, Taylor's skirt blew up, briefly exposing a portion of Taylor’s underwear!  “We have wind machines for a few songs in the show and they weren’t supposed to be on during that song,” Taylor said. “I walked over thinking it wasn’t on and it just kind of blew it up a little bit. I was just sort of like, ‘Well, that’s new’ and just continued on with the show.”    Read about it here.  She also talks about the rumors she is allegedly back with Twilight's Taylor Lautner.  Something she denies, darn it!   http://www.youtube.com/watch?v=ovbtmQEXSEY