What is the worst noise people do with their mouth?

I had a friend who ate cereal in the most fucked up way imaginable. He'd put dry cereal in a bowl, then pour a glass of milk, then put one spoonful of dry cereal into his mouth and add milk from the glass.

Listening to him making this

"Glunk, gloop, glooop, glooooook, gloooooooonk"

noise while he swilled it around his mouth and chewed is the worst thing I've ever heard.