I'll preface this by saying that I once heard a stand-up comedian make a joke about your head leaking maple syrup at night, and it opened my mind to a whole new reality. I wasn't the only one. And really it would have been a shame if I was, because that would mean that either I had some kind of super rare skull leprosy or my brain was trying to summon one of the Outer Gods and the portal was only opening wide enough for Shub-Niggurath to ooze one or two tentacles through.
The longer you own a pillow, the more like a turn of the century East Asian crime scene it will become. Every time you change your pillow case, you're pulling out a fluffy, comfy cloud that looks like it's been yanked straight from the asshole of Zeus himself after a rough night of low quality mead and Olestra burritos. It's yellowed and faded and terrifying, with wet filth patterns on it that seem to indicate that your hair spends all night releasing low volumes of oily piss to pass the time.
You can feel your back door puckering in anticipation.
Logic dictates that you're probably just releasing head pee as a sort of relaxational process your body likes to go through as you wind down at night, because your body is a wonderland of gross when you're not paying attention to it. That's the scientific explanation for farts, incidentally -- your body attempting to be funny. Usually it works. Farts are hilarious. Or maybe it's just because your hair is naturally a bit greasy and if you hold something against it for eight hours a day, every day, it's going to get greasy, too. Feel free to test this theory by taping a swatch of cotton to Ron Jeremy's back for part of the day and see what it looks like when you're done. Just revolting.