Catch Santa At Your House

For the past couple of years, I have "caught" Santa putting gifts under the tree. It has now become a thing to where my son asks if I saw him putting the gifts under the tree. How can I say no? 

There's an app called Catch Santa (iPhone and Android). I take a picture of my house (anywhere I want) and then place the Santa photo (different positions) in the place where it looks most real.

Literally, in seconds, it appears as if I caught Santa at home.