roguish
Playfully naughty and charming while breaking small rules.
Roguish describes someone who behaves in a playfully mischievous way, breaking minor rules with charm and a twinkle in their eye. A roguish person might bend the rules without quite breaking them, or get away with small acts of harmless trouble because they're so likable while doing it.
Picture a student who sneaks an extra cookie from the cafeteria with such a cheerful grin that even the lunch monitor can't help but smile. Or think of a character in a story who bends the law but somehow makes you root for them anyway. That's roguish behavior: a little bit naughty, often clever, but never truly mean or dangerous.
A roguish smile suggests someone is up to something, but probably nothing too serious. A roguish character in a book might be unreliable and unpredictable, yet somehow endearing.
When you call someone roguish, you're usually noting their charm as much as their misbehavior. It's mischief with style.