Two nights after Jay-Z  dazzled South by Southwest with an American Express-sponsored show on Monday night (Mar. 12), his "Watch The Throne" partner, Kanye West , made an unannounced appearance during New York venue S.O.B.'s 30th anniversary showcase Wednesday night at the Belmont in Austin.
At around 1:30 am CST, West and rapper Big Sean  joined 2 Chainz, a new signee to Def Jam's roster, onstage, leading to dozens of flip cams springing up from the surprised audience.
• PHOTOS: The Scene From Austin 
After West and Big Sean bestowed 2 Chainz with some kind words (sort of like the props Raekwon  gave The Artist Formerly Known as Tity Boi at his New York show in January), Sean launched into "Dance (A$$)," then "Marvin Gaye & Chardonnay" with West. Yeezy, dressed in a black tux, then took center stage for his "Graduation" single "Can't Tell Me Nothing."
The S.O.B.'s showcase also featured buzzworthy hip-hop/R&B acts like Machine Gun Kelly, Miguel and Elle Varner. Joe Budden, a member of headlining rap supergroup Slaughterhouse, apparently tipped fans off to West's impromptu appearance by posting on Twitter , "Just had a pretty deep talk w Kanye..... That was dope."
West, who will head to Europe in May on the next leg of his "Watch The Throne" tour, performed alongside Jay-Z at SXSW in 2011.
- SXSW