Zac Efron made his way through Heathrow Airport in London with a smile today. He was sporting his bold zebra-stripe Prism sunglasses after the long flight from LA. Zac's been busy promoting The Lorax recently, with his latest stop on Conan, where he chatted about his crazy female fans and showed off his singing skills with a version of The Beach Boys' "Barbara Ann." This week Zac also met up with his costar Danny DeVito at the NY Public Library for a reading of the Dr. Seuss book that inspired the film. Zac will soon switch gears from his kid-friendly movie to a more adult project ahead of the April release of The Lucky One, which is based on a popular Nicholas Sparks novel.