Many young voters may know Kal Penn from his role in the movie "Harold and Kumar Go To White Castle" or his role on the show "House." But on Tuesday, he played the role of surrogate for President Obama, opening on a light note and ending on a serious one.

"I am honored to accept your nomination for president of the United States," he joked. "Wait, this is not my speech."

In his actual speech, Penn praised Obama's record on immigration, education, and other issues, and underscored the importance of getting involved with the campaign.

"I volunteered in Iowa in 2007, because like you I had friends serving in Iraq," Penn said. "I had friends looking for jobs, others who couldn't go to the doctor."

He also made the night's first Clint Eastwood joke, saying "Thank you, invisible man in the chair."

Penn spoke directly after Chicago Mayor Rahm Emanuel. He joked that now that Emanuel is mayor, he can't use four letter words anymore. So Penn said he would offer one: "Vote."