The door into face method means we start by making a very big request that is likely to be turned down. We then follow up asking for something similar but much smaller. Because the person feels bad for rejecting our initial request (slamming the door in our face), and because we were willing to reduce our request, the person feels compelled to reciprocate by agreeing to our second request . Door in the face also works because of framing: compared to a very large request, a subsequent small one sounds more acceptable.
For the door in the face request to work, the two requests have to be made by the same entity.

Read more about how it works: