A "cheeky smile" refers to a mischievous, playful smile that might indicate a person is up to something.
Sentences with «cheeky smile»
The bespoke ice cubes were crafted in the shape of Richard Branson's face, complete with cheeky smile and flowing locks. (thetravelmagazine.net)
When asked about summer transfers wenger had that same cheeky smile he had when we ended up signing ozil. (justarsenal.com)
However, even if I have learnt to eat scorching hot or cold meals, I have barely any money to spend on myself, I have never before existed on so little sleep and have to take a car load of things on a trip out, I wouldn't change it for the world, to see that little cheeky smile every morning. (mummymiller.com)