Back to the Marauders

A magical experiment sends Harry, Ginny, Neville, Ron, and Hermione back to the time of the Marauders. They promptly run into the four biggest mischief-makers in Hogwarts History, (the Weasley twins came in a close #2) a batlike git, the Prefect Evans with her infamous eyebrow, and the slightly mental but brilliant professor with a lemon drop obsession. Well. It worked! Now what?