Save a rug neuter your cat Neuter. Because all the other answers are stupid. Litter's just another word for trash. Smarties neuter, dummies don't. Pet overpopulation isn't the end of the world, unless you're a puppy or a kitten.
Prevention is wiser than destruction.
Please neuter your pets. We will no longer kill your mistakes and the casualties of your irresponsibility. Friends don't let friends have litters. Help us put the human back in humane, neuter your pets. March in and Neuter.