I would often hear my ex-boyfriend making a blowing sound in bed at night. He always said he was blowing his nose into his t-shirt. I thought that was gross, but whatever.
Then, when he moved out, I was horrified to discover that he was actually blowing it into his hands and wiping it onto the back of the fabric headboard of my bed! His side was covered in so much disgusting, crusty snot. I left it there. There was no way I could clean that!