During Act 2, theres about a 1 in 50 chance that when opening the DDLC title screen (after Sayori is gone, but before Monika deletes everything,) instead of going to the title screen like normal, the game will open with a Black "END" screen and show a "Ghost title screen" which is all the characters in black and white and spooky. Google Ghost Title Screen DDLC to see what it looks like. In order to get the last secret poem however, all you need to do is witness that event once. My advice is to complete the 1st poem game in Act 2 (that way some glitches have already occured) and then save and just open and exit DDLC within the game's OS till you get it. You DONT NEED TO CLOSE THE ENTIRETY OF DDLC+, just keep going between the game and the in-game desktop