Ewan just listened for a moment as the some of the other children gave various answers and then raised his hand to answer himself.

Sneaky? ”How about give a ridiculous amount of homework right before a test? okay, that was just a joke but you know, kind of funny too.

Now for an actual answer. ”Someone could use the fidelius charm. It’s difficult and complex to use but it could be used to conceal a secret inside an someone’s soul”. Would this be classed as sneaky? Possibly. It would really depend on the secret you were hiding.