Hah! It was sort of an "easter egg" feature that we added way back when we released DisplayFusion on Steam. It just adds a function to the list on the Settings > Functions tab. When you run it on a window the window hides and there's a hat icon in its place. Double-clicking the hat restores the window. It's like the Rollup Window to Icon function but with a hat instead

The original function (Rollup Window to Icon) is there for folks that want to shrink the app into an icon that they can just position out of the way. They can then restore the window by double-clicking the icon. It's not for everyone obviously, but it's there for folks that wan to use it. The Rollup Window to Hat function is just a silly play on the Rollup Window to Icon functionality.