When the mighty Ogrelord Shrek returns to judge all who do not preserve their layers.
Humans have layers. Shrek's shrock pleasures your layers. If you do not have many layers, you will not be spared. Eat onions to add on to and preserve your layers, for the Shrekoning is among us.
The Dutch try to get American tourists to say it for their own pleasure and laughs. They can't. You have to have the "schhuuchhh" in your throat (like a bug is in there). Don't try because you'll practice for a long time and get nowhere. I tried.
Once only a humble Internet meme, The Shrekoning now defines the transcendence of one's mind to a new plane of existence to live in the Holy Swamp of our Lord Shrek.