Purrvert

A cat who likes to hump things such as a favorite toy, blankets, other animals or even people. Usually male cats more commonly have this trait. Sometimes the cats make loud sounds that are thought to be mating calls which typically happen at night or when the stimuli is around. The aroused cat will sometimes display an erect penis. These cats are also known as feline sex addicts, which could actually be from a psychological problem such as trauma or abandonment. Also, the behavior could simply mean the cat is showing dominance. Lastly, your cat may still have sex hormones present in his body after surgery. The hormones that govern sexual behavior in your cat aren't completely gone the moment that he is neutered.

Fred: I keep getting woken up in the middle of the night to my cat screaming and humping his favorite tiger toy. Is something wrong with him?

Jill: If he still has his balls, he wants to go out and mate. If he's been neutered for a few years, you're cat is probably just a typical purrvert.

Nipaholic

A cat who is very addicted to catnip

Me: My cat is able to untwist the lid and open up the catnip jar himself.

Crazy Cat Lady: Sweety, your cat sounds like a nipaholic. If cats claw through the plastic cat nip bags, they're a typical cat and no need to worry. If they are able to open lids to get to it, you have a classic feline drug addict living in your house.