This is so cool! Apparently these people just moved and decided to use their empty boxes to decorate for the upcoming holiday. Someone on Reddit asked them how they made it and here's what one of the people said:
Hi there! I'm the one who made the monsters. I used contact paper, tissue paper and modge podge for the eyes. I used cardboard, black paint, and duct tape for the rest! You can't see them from the inside of the house because there are curtains behind them.
Here's a picture of the house in daylight that was provided as well.
There's more information available in the thread on Reddit.
How cool is this? Hope this helps to get you all in the Halloween spirit!