Technically, Jason Mamoa doesn't turn 40 for a few more days, but his friends couldn't resist throwing him a surprise birthday party! Guests at the party included his "Game of Thrones" co-star Emilia Clarke and former "Vampire Diaries" star Ian Somerhalder. A YouTube video showed Mamoa's reaction to the surprise: at first he curses but then he can't stop smiling! In the video, he Facetimes his wife, Lisa Bonet, to show her the scene, including a slideshow his friends put together.