speak of the devil

Prov. Talk about a certain person, and that person appears. (Used when someone appears whom you have just been talking about.) Alan: I haven't seen Bob for weeks. Jane: Look, here comes Bob right now. Alan: Well, talk of the devil. Hi, there. We were just talking about you. speak of the devil and in he walks.

the person we are talking about has just arrived Well, speak of the devil, here's Patrick now.

something that you say when a person you are talking about arrives and you are not expecting them Apparently, Lisa went there and wasn't very impressed - oh, talk of the devil, here she is.

The person just mentioned has appeared, as in Why, speak of the devil-there's Jeannie. This expression is a shortening of the older Speak of the devil and he's sure to appear, based on the superstition that pronouncing the devil's name will cause his arrival on the scene. The figurative use was already explained in James Kelly's Scottish Proverbs (1721).

Acknowledgment of someone's unexpected arrival. The complete expression is “speak of the devil and he will appear,” which is nothing that superstitious people wanted to have happen. As such a cautionary tale, the expression was not used in jest until the late 19th century. That's when responding to an unanticipated appearance with “speak of the devil” lost its dark satanic connotation.