Cementing his reputation as one of the most likable actors ever, Johnny Depp showed up unannounced in full Jack Sparrow costume after receiving a letter from a nine-year-old girl at a British school near the set of Pirates of the Caribbean: On Stranger Tides. The letter asked for help staging a mutiny against the teachers, but Depp advised her against that since there were cops outside watching him. The letter did not ask for a lesson in dental hygiene, but the kids got one anyway. Bonus! The video is after the jump -- prepare for your heart to melt.