suppermariobroth:

At the beginning of Good Egg Galaxy in Super Mario Galaxy, Mario can approach a house, where standing in front of the door makes a “Read” icon appear. Pressing A, Mario will then read a message the owner left on the door. However, what is really happening is that the developers took a shortcut: instead of programming a readable door object, they hid a signpost, the default readable object, inside the house. Mario is interacting with the signpost through the door, making it appear as though he was reading the door.