I was messing around on my computer today and randomly clicked the OS X desktop while holding down the Option key. The current window disappeared. My old way of doing this was to minimize the window using Cmd + M.
It appears that to quickly hide the current window (in most programs) all you have to do is hold the Option key and left mouse click on the desktop. Window hidden.
If you have multiple windows open then you’ll have to perform this action multiple times with the window ‘active.’ It will not work if you see ‘Finder‘ in the title bar.