A lighthearted, fun episode is a lark. You could describe the wonderful day you spent with friends exploring little fishing towns along the coast of Maine as a lark.
Often unplanned, a lark can happen when you are feeling adventurous. You might decide on a lark to audition for a reality show — and be picked! The act of trying something new like this can also be called larking. A lark is also a kind of songbird. Using lark to describe carefree fun might come from 1800s sailors' slang, skylark, to describe playing in the rigging of the ship, up high like a lark.