"He was filming a scene and talking on his cell phone," the source said. "None of the other Entourage cast was [there]. He was really nice."
Details on Efron's role are yet to be announced, but he joins a healthy roster of boldfaced names set to appear as themselves during Season 6, including Lil Wayne, LeBron James, Tom Brady and Aaron Sorkin.
A rep for the show did not immediately respond to TVGuide.com's request for comment.
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