Speak Of The Devil | English Idioms
You are talking about somebody and then that person suddenly appears. In such a situation a native English speaker might say speak /talk of the devil. Actually this is an incomplete phrase. The full forms are speak of the devil, and he shall appear and talk of the devil, and in he walks.
Many Indians believe that if a person walks in when you are talking about him, he would live to be 100. Interestingly, Indians sometimes say a hundred years in such a context. Remember that native English speakers wouldn’t use this expression. They are also unlikely to understand its meaning if you use it in front of them.