Here is what I wrote in an email recently to attempt to explain my cat's unusual sexual predilections:
"Ivan has only been in my life for a couple years and he came with some unique habits. As a kitten, Ivan had a stuffed bone (I think it was meant to be a doggie chew toy) that he cuddled with and ultimately began using to um, satisfy himself sexually. Well, the kitten grew in size, but alas the bone did not. Ivan's previous owner discovered that Ivan had graduated to his mother's stuffed animal collection (creepy, I know, not so much the humping as the existance of a grown woman's stuffed animal collection). That wouldn't do, so a special trip to goodwill was made and that is how Ivan came to have his very own hump bear. But here's the interesting part. Ivan holds the stuffed bone in his mouth while he humps the teddy bear. He also carries around the disgusting, threadbare, crusty-with-god-knows-what bone in his mouth such that I find it in random places in my apartment. But when he leaves the bone on top of the bear, you know what he's been up to when you weren't looking.
So Kelsey is correct, Ivan doesn't hump other cats. However, I've never seen him around another cat. Chances are, the bone and bear are simply poor substitutes for the really thing. So probably best for your cat to steer clear. In fact, I advise most creatures to steer clear of Ivan because he really only gets along with his bear and himself (no, not even me most of the time). So while flattered that you want to meet him, don't say I didn't warn you if he tries to bite you."
In related news, a guard dog at a children's museum did what dogs do and chewed up a teddy bear collection (Ivan's nightmare really- so many hump bears laid to waste by, of course, a dog). The difference being that this was a rare and valuable collection of teddy bears. The photos taken in the museum after the massacre are hilarious. The dog is standing there with a look on his face like, "What? You mean that $75,000 teddy bear that was once owned by Elvis wasn't meant to be a chew toy to help me pass time on the graveyard shift?". The King's bear, by the way, was on loan from a collector. Yikes.