Yours is the 2015 version of the 1980s-era DOS app that displayed a fake word processor UI with the top portion of a fake but intriguing letter visible. You would leave this app running and then leave for lunch. An office snoop would see the fake letter and want to read more, then press a key to scroll down, which would activate a siren sound on the PC speaker and display some silly "you're busted" message on the screen.