To look at or browse your desktop files and documents when your internet is down, while either waiting for your internet connection to be restored or if you're just bored.
The internet has been down all day, I've been surfing the desktop in the meantime. I even found some videos I forgot I had downloaded.
He received a text from his girlfriendreminiscing about the amazing sex they had had the previous evening which resulted in an awkward 'desktop popup' erection.
When spotting a picture perfect image, whether it be moonlight on a lake, or whatever you think would make a good image as a background setting on your desktop (Computer).