in a way that suggests that you know secrets

She grinned slyly and refused to tell me where the money came from. 她狡黠地咧嘴一笑，拒绝告诉我钱是从哪里来的。

They look as if they're remembering a joke, grinning slyly to themselves.

in a clever way, especially when it deceives people in order to get what you want

Two police officers catch them, but the criminals slyly explain their way out of it.

a slyly subversive new book for children four to eight years old 为四至八岁儿童编写的一本狡猾的颠覆性新书