It all started with that hour of detention you got from Professor Snape, who overheard you make a joke about his greasy hair.  You had to miss dinner to do the detention, and now it's midnight, and you are wide-awake in your four-poster bed.  Your stomach won't stop grumbling. Didn't Fred and George Weasley sometimes sneak into the Hogwarts kitchens for snacks?   So why can't you?  Sure, you don't exactly know where the kitchens are, but it'll be fun to explore the castle at night.