Curmudgination
The imagination of a curmudgeon or old person. Usually applies to something that only an old person would think of.
Grandpa: Robots are trying to break down the door!
Dude: Gramps, no one is at the door. It's just your curmudgination.
Dude: Gramps, no one is at the door. It's just your curmudgination.