Short answer: It’s an old private joke.
Long answer: This one time, at band camp… Actually, it was more than twenty years ago at science camp. I was sharing a room with the brilliant Yoad Lustig (AKA “The Voice of Reason”) and somehow the color of my eyes became a subject of debate. Yoad settled the debate by announcing that my eyes were “murky grey”. He apologized later (publicly, in the science camp yearbook) and proclaimed that my eyes were fine and that “… there is nothing wrong with some mold on one’s contact lenses” (I was wearing RGPs at the time).