Flapjack reminds me a lot of Maakies/Drinky Crow (old-school sailors in a world of pure nonsense) but with restraints on the humor. Those restraints are there for its own good, and ours. It is constantly testing the limits of said restraints, though, which is also for the best. Kind of like Rocko's Modern Life, except it tries to get away with creepy and disturbing humor instead of satiric sex jokes.
They are hopelessly, almost tragically addicted to candy. The local bar serves big random piles of candy in beer glasses. His pirate mentor keeps a hip flask full of syrup on him at all times. He considers it his best friend.