At TechCrunch Disrupt, HBO's Silicon Valley actor T.J. Miller shared a story with TechCrunch founder Michael Arrington about the time he ran into Tesla founder Elon Musk in Silicon Valley — and had no idea who he was.

Miller says he was walking around Silicon Valley and saw a guy who looked like he fit into the tech scene. He asked the person — who turned out to be Musk — if he had seen his show. Musk said that he had. Miller then asked if Musk would be willing to make a cameo. Musk said he wouldn't because it "wasn't realistic enough," Miller said.

After Miller walked away, someone else came up to him and said, "You know that was Elon Musk?"

"I was literally like, 'Who's that?' And someone was like, 'He invented the Tesla.' And I was like 'Ohhhh...what is that?'" Miller joked on stage at TechCrunch Disrupt.

The show "Silicon Valley" has had a number of tech celebrities make cameo appearances, including Arrington, Re/Code co-founder Kara Swisher and Google executive Eric Schmidt.