Twitter co-founders Evan Williams and Biz Stone aren’t just tech entrepreneurs, they can also party like rock stars. The social media moguls showed up at the XS nightclub at Steve Wynn’s Encore resort in Las Vegas with a group of friends in the early hours of Sunday, and spent hours dancing on the stage during Avicii’s DJ set, reports The Post’s Andy Wang. XS co-owner Jesse Waits set up a table for them right next to the stage, where Williams and Stone and their male pals toasted numerous bachelorette parties and the Swedish DJ with glasses of Champagne and shots of Patron. Earlier that night, Williams and Stone, who have just revealed their new social startup Lift, dined at The Cosmopolitan resort’s Blue Ribbon restaurant.