That has never happened - to me :) But before my wife and I got married, I had a single cat. He once proceeded to use Karen's sweater as a urinal. Fortunately it was in the bathtub being laid out to dry after being washed.
I maintained that it just looked and felt like a cat box. She maintained that there was some additional meaning to the act :) I think she may be right.
I've often heard of shoes being the target of a cat's expressions of jealosy.
This shot was taken several generations of digicam back and when I go back and play with these older digital photos, I'm always reminded of how much I love the 20D! Jim H.