President Obama Saturday provided a few laughs at the Gridiron dinner in Washington, poking fun at himself, Vice President Joe Biden and former Secretary of State Hillary Clinton. He even took a poke at birthers who have long claimed Obama was born in Kenya, saying, "If I did not love America, I wouldn't have moved here from Kenya."

The president shared the head table with several dozen people, including Wisconsin Gov. Scott Walker, who is considering a bid for the 2016 Republican presidential nomination. Alluding to Walker's decision not to say whether he believes in the theory of evolution, Obama said he thinks not answering the question "is a problem. I absolutely believe in the theory of evolution -- when it comes to gay marriage.”

Obama said he thinks he's funnier this year than in the past. “I’m not saying I’m any funnier. I’m saying weed is now legal in D.C.,” he joked, and then went on to discuss his advancing years: “Just a few years ago I could never imagine being in my 50s. And when it comes to my approval ratings, I still can’t.”

Obama said he had always thought of himself as tech-savvy but is not so sure now that the Clinton's use of a private email address and personal server during her tenure in the Cabinet has kicked up controversy. “Hillary has a server in her house! I didn’t even know you could have one of those. I am so far behind," he lamented.

He also joked Biden "rubs my shoulders, too," a reference to a picture that captured the vice president rubbing the shoulders of Stephanie Carter as her husband, Ashton, was being sworn in as defense secretary.

On a more serious note, Obama said there was nothing funny about the letter signed by 47 Republican senators this week and sent to Iranian leaders amid delicate talks to rein in Tehran's nuclear program. “You don’t diminish your office by taking a selfie. You do it by sending a poorly written letter to Iran. Really. That wasn’t a joke,” the president said.