Katy Perry Dons Latex Ballot Dress For Barack Obama
He joked: "I've got to know Katy and she's a wonderful young lady. And I can tell that part of it is because of her outstanding grandma, a 50-year resident of Nevada.
"The only thing I have to say is she got some lipstick on me when she kissed me. Fortunately somebody wiped it off before Michelle saw it. I'm telling you, you're going to get me in trouble!"
After appearing at the event, Katy - whose birthday is today (25th October) then tweeted: "So tonight was a great night! The PRESIDENT gave grandma and I unforgettable shout outs & now I am officially 28! Best. birthday. ever."