Talk of the devil and he'll be sure to appear.

Someone who was just being discussed turns up unexpectedly, as though mentioning them had summoned them.

The saying draws attention to the timing of the arrival. It does not imply that the conversation caused it or that the person is wicked.

Say it when someone arrives just after others have mentioned them. It can be a lighthearted remark about the coincidence, though it may feel awkward if the conversation was unkind.