Boogermeow
The sound your nose makes when you're lying down and breathing in, and you mistake it for a cat.
My roommate has cats, but I ALWAYS keep my door closed to keep them out. Then, one morning, I woke up to the sound of a cat really, REALLY close to me. I looked around, but found one not; Upon further investigation, I realized that it was, in fact, a boogermeow.